Low density fluid displacement to store or generate power

ABSTRACT

The present invention relates to systems and methods for pumping or removing a fluid from a region within or on top of or in contact with a water or liquid body and applications for said systems and methods. Some embodiments may also relate to anti-fouling or reducing fouling structures like docks.

CROSS REFERENCE TO RELATED APPLICATIONS

The instant application claims priority to provisional application No. 62/670,133 filed May 11, 2018 which is hereby incorporated by reference in its entirety. The instant application is a continuation-in-part of Ser. No. 16/776,078 filed Jan. 29, 2020 which is a continuation of U.S. Ser. No. 16/409,790 filed May 11, 2019 which issued as U.S. Pat. No. 10,562,511 on Feb. 18, 2020 all of which are hereby incorporated by reference in their entirety.

BACKGROUND OF INVENTION

Scaling, fouling, other ‘growths’, and corrosion can be damaging to water infrastructure and other liquid infrastructure. Scaling, fouling, other ‘growths’, and corrosion can reduce infrastructure lifespan, infrastructure structural integrity, the efficiency of boats and other water vehicles through increased drag and weight, clog pipes, and reduce the buoyancy of docks and buoys.

Prior art technologies for preventing scaling, fouling, and other ‘growths’ include anti-foulants and antiscalants. Anti-foulants and antiscalants have multiple significant disadvantages. They are generally bad for environment and may be toxic to aquatic ecosystems. They are generally only temporary and require re-application or replacement for continued effectiveness. They are generally expensive, including due to material cost, application cost, and their temporary nature.

In docks and other permanent or semi-permanent aquatic infrastructure, it is common to not employ anti-foulants and antiscalants. Generally, barnacles and/or other growths are periodically removed from the bottom of docks. Barnacles and other growths can add significant weight to docks and can damage or puncture dock pontoons. Removal is expensive, labor intensive, and only a temporary solution.

SUMMARY OF THE INVENTION

The present invention relates to systems and methods for pumping or removing a fluid from a region within or on top of or in contact with a water or liquid body and applications for said systems and methods.

Some embodiments may be applicable to, for example, inhibiting or preventing growth formation or fouling of structures in liquid environments. Said liquid environments may comprise aqueous and/or non-aqueous environments. Some embodiments described herein may inhibit or eliminate or prevent growth formation or fouling without the need for coatings, paint, manual cleaning/scrubbing, or other methods described in the art. Growth formations may include, but are not limited to, one or more or a combination of the following: marine growths, foulants, marine creatures, marine animals, inorganic scaling, organic scaling, barnacles, mussels, clams, oysters, worms, shrimp, crustaceans, biofilms, algae, bacteria, fungi, or ameba. Moving parts for said embodiments related to inhibiting or preventing growth formation or fouling or corrosion of structures in liquid environments, such as pumps and generators, if desired, may be located entirely above the surface of a water or liquid body.

Some embodiments may be applicable to, for example, increasing or decreasing the height of a floating structure, such as a dock. Some embodiments described herein may involve increasing the height of a floating structure above the surface of a liquid by pumping air into a concave region within or beneath said floating structure such that the air or other gas or other low-density fluid at least partially displaces a portion of water in said concave region. Similarly, the height of a floating structure above the surface of a liquid may be decreased by allowing gas to escape from or by pumping gas out of said concave region. Air or other gas may be transferred in or out of said concave region using one or more tubes. The concave region may be open to the water or other liquid. If advantageous, the pumping or release of gas may be conducted using moving parts entirely outside of the water or liquid body. By having moving parts outside of and not in contact with water or the liquid, the moving parts (e.g. air pump) may comprise lower cost equipment, may be less susceptible to fouling, and may have a longer lifespan.

Some embodiments may be applicable to, for example, an energy storage device. Some embodiments may involve a storage region beneath the surface of a water or liquid body and a storage region near the surface or above a water or liquid body. To ‘charge’ said energy storage device, low density fluid, such as a relatively lower density liquid or a gas, may be pumped into said storage region, displacing a higher density fluid, such as water. To discharge said energy storage device, said higher density fluid may be allowed to displace said lower density fluid, generating electricity due to the flow of the lower density fluid through an electric generator. Moving parts for said energy storage device, such as pumps and generators, if desired, may be located entirely above the surface of a water or liquid body.

Some embodiments may be applicable to, for example, a tidal power energy generation system, which generates energy from change in water level due to, for example, tides. Some embodiments may involve using the displacement of air or other fluid from a storage region due to a rise in water level due to tides to generate energy, such as electricity. Some embodiments may involve using the movement of air or other fluid into a storage region due to a decrease in water level due to tides to generate electricity. Moving parts for said tidal power system, such as pumps and generators, if desired, may be located entirely above the surface of a water or liquid body.

It is important to note that embodiments described herein may be combined and the systems and methods described herein may overlap or have multiple simultaneous applications.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1: An example dock with a concave region ‘gas pocket’ (3′) on the bottom of each float or pontoon.

FIG. 2 (above): An example dock with a concave region ‘gas pocket’ (3′) on the bottom of each float or pontoon with air pump and tube interconnected.

FIG. 3: An example embodiment with extended ‘walls’, which may be employed to prevent air or gas losses in the event of, for example, waves, turbulent water, or a significant change in the angle of the dock.

FIG. 4: An example embodiment where changing the volume of gas in a gas pocket adjusts the height above the liquid surface and/or angle of a floating structure, such as a dock. FIG. 4 may show height increasing.

FIG. 5: An example embodiment where changing the volume of gas in a gas pocket adjusts the height above the liquid surface and/or angle of a floating structure, such as a dock. FIG. 5 may show height decreasing.

FIG. 6: An example simplified setup of an embodiment employing a lower density liquid and a higher density liquid.

FIG. 7: Step 1: FIG. 7 may show an energy storage embodiment undergoing charging.

FIG. 8: Step 2: FIG. 8 may show an energy storage embodiment at a relatively charged state.

FIG. 9: Step 3: FIG. 9 may show an energy storage embodiment discharging.

FIG. 10: Step 4: FIG. 10 may show an energy storage embodiment at a relatively discharged state.

FIG. 11: FIG. 11 may show an example embodiment where the LDL and/or HDL storage regions at a higher head height or above the surface are located on a platform or a floating platform.

FIG. 12: FIG. 12 may show an example embodiment where the LDL and/or HDL storage regions at a higher head height or above the surface are located on land.

FIG. 13: FIG. 13 may show an example embodiment where multiple subsurface storage regions are employed for energy storage and/or chemical storage.

FIG. 14: Step 1 (Higher Tide, Filling, And Electricity Generation): FIG. 14 may show an embodiment where electricity is being generated.

FIG. 15: Step 2 (High Tide, Cavity Full): FIG. 15 may show an embodiment where the storage region is nearly full with water.

FIG. 16: Step 3 (Lower Tide, Emptying, Generating Electricity): FIG. 16 may show an embodiment generating electricity when the surrounding water body water level is relatively low compared to the water level inside the storage region.

FIG. 17: Step 4 (Lower Tide, Empty): FIG. 17 may show an embodiment where the storage region is nearly empty with water.

FIG. 18: Step 4 Alternative (Lower Tide, Empty, depending on time of year and location): FIG. 18 may show an embodiment where the storage region is fully empty with water.

FIG. 19: Step 5 (Lower Tide, Pump remaining water out): FIG. 19 may show an embodiment where air is pumped into a storage region to remove or displace residual water.

FIG. 20: Step 1 (Higher Tide, Filling, Electricity Generation): FIG. 20 shows an example embodiment where water/air cavity or storage region contains a porous material.

FIG. 21: Step 2 (High Tide, Cavity Full): FIG. 21 shows an example embodiment where water/air cavity or storage region contains a porous material.

FIG. 22: Step 3 (Lower Tide, Emptying, Generating Electricity): FIG. 22 shows an example embodiment where water/air cavity or storage region contains a porous material.

FIG. 23: Step 4 (Lower Tide, Empty): FIG. 23 shows an example embodiment where water air cavity or storage region contains a porous material.

FIG. 24: Step 1 (Higher Tide, Filling, Generating Electricity): FIG. 24 shows an example embodiment where water/air cavity or storage region is located on or within a water body.

FIG. 25: Step 2 (Higher Tide, Full): FIG. 25 shows an example embodiment where water/air cavity or storage region is located on or within a water body.

FIG. 26: Step 3 (Lower Tide, Emptying): FIG. 26 shows an example embodiment where water/air cavity or storage region is located on or within a water body.

FIG. 27: Alternative Step 3 (Lower Tide, Emptying, Depending on Tide and Location): FIG. 27 shows an example embodiment where water/air cavity or storage region is located on or within a water body.

FIG. 28: Step 4 (Lower Tide, Empty): FIG. 28 shows an example embodiment where water/air cavity or storage region is located on or within a water body.

FIG. 29: FIG. 29 shows an example embodiment with a floating pump or generator station.

FIG. 30: FIG. 30 shows an energy storage system where the first storage reservoir is located on land and the pump and/or generator is located on land.

FIG. 31: FIG. 31 shows an energy storage system where the first storage reservoir is located on land and the pump and/or generator is located on land.

FIG. 32: FIG. 32 shows an energy storage system where the first storage reservoir is located near, at, or beneath the surface of a water body and/or the pump and/or generator is located near, at or beneath the surface of a water body.

FIG. 33: FIG. 33 shows an energy storage system where the first storage reservoir is located near, at, or beneath the surface of a water body and/or the pump and/or generator is located near, at or beneath the surface of a water body.

DETAILED DESCRIPTION OF THE INVENTION First Description of Embodiments

An example embodiment may involve ‘walls’ connected to the bottom or sides of a liquid structure. A liquid structure may include, but is not limited to, one or more or a combination of the following: floating structure, a dock, buoy, platform, float, boat, flat bottom boat, skiff, or surface structure. A liquid structure may also include structures which are anchored to land or at least partially supported by land, while also being in or near or in contact with water or immersed in water or in contact with water or in contact with another liquid.

In an example embodiment, the structure may be a dock (please note: a dock is provided as an example floating structure, the elements of the embodiment described herein may be applicable to other floating or non-floating structures described herein). Connected or as a component of the dock or as a feature of the shape of the bottom of the dock are ‘walls’ which may be connected to the side or bottom of the dock or near the perimeter of the bottom of the dock. Alternatively, the shape of the bottom of the dock may be tailored to have said ‘walls’, as in, for example, said ‘walls’ may be part of the shape of the dock rather than a connected separate material. Said ‘walls’ may protrude beyond the vertical water depth of most or all of the floating dock in contact with the water. The connection of the ‘walls’ to the structure may be ideally air or water tight. Said ‘walls’ may simply comprise a concave structure or protruding portions of a concave structure.

Said walls may result in the formation of concave region or cavity located, for example, near the bottom of a floating structure or comprise most of the bottom of a floating structure. In the present embodiment, a gas may occupy at least a portion of said concave region. Said gas may include, but is not limited to, one or more or a combination of the following: air, nitrogen, water vapor, methane, hydrogen, flue gases, carbon dioxide, oxygen, inert gas, argon, helium, practically water insoluble gas, hydrocarbon, ozone, or a combination thereof. The gas may be at least temporarily or semi-permanently or practically permanently ‘trapped’ in said concave region. Said ‘trapped’ gas in said concave region may be referred to as a ‘gas pocket’ or an ‘air pocket’. Said gas remains in said concave region due to, for example, 1) greater density of water than the gas; and/or 2) the gas' practical inability to pass through the water/gas interface; and/or 3) the relative gas tightness or gas tight seal of the concave region.

An operating principle of the air pocket may be demonstrated by using a simple empty drink cup and a container filled with water. When an empty drink cup is flipped upside-down and submerged beneath the surface of the water in an upside-down position, air in said drink cup may be trapped inside said drink cup as water may be unable to replace said air because the air cannot escape upward through the drinking cup. Said trapped air may be an example of an air pocket and the region inside the cup where the air is trapped may be an example of a concave region or cavity. An example application where said air pocket effect has been employed in prior art may include ‘diving bells’.

Said gas pocket or air pocket may result in the formation of a separation or non-contiguous separation between the water and at least a portion of the surface of the concave region. Water may be separated from contact with at least a portion of the solid surface of the of the concave region due to the physical separation or barrier of the gas pocket between the water and said solid surface. A significant portion of the surface area of the solid surface of the concave region may be in contact with said gas pocket. A significant portion of the surface area of water displaced by the air pocket may be in contact with the air pocket at an air—water interface. Said concave region or surface area in contact with said gas pocket may comprise a significant portion of or nearly all the surface area of the bottom of, for example, the bottom of a surface structure. Said concave region or surface area in contact with said gas pocket may comprise a significant portion of or nearly all the surface area which may be exposed to or vulnerable to or would otherwise be in contact with water or other liquid. Said significant portion may comprise greater than 5%, or greater than 10%, or greater than 20%, or greater than 30%, or greater than 40%, or greater than 50%, or greater than 60%, or greater than 70%, or greater than 80%, or greater than 90%, or greater than 95% of the bottom of the surface of a structure in contact with a liquid or water body.

Fouling or scaling or growth formation may be inhibited by said separation or non-contiguous separation between the liquid and at least a portion of the surface of the concave region resulting from, for example, said gas pocket. Fouling or scaling or growth formation generally occurs in a water environment when water is in direct contact with a solid surface. Said air pocket enables a substantial surface area of water, which may otherwise be in contact with solid surface, to be in contact with a water—gas or water—air interface rather than with a solid surface. Said gas separation or air barrier prevents liquid-borne or water-borne foulants or scalants or growths to adhere the said solid surface. Said concave region may comprise at least a portion of the surface area of the bottom of a floating structure or structure in contact with liquid. Said concave region may comprise a substantial portion or most or almost all the surface area of the bottom of said floating structure or structure in contact with liquid, which may enable a substantial reduction in fouling or scaling or growth formation relative the same structure without a gas pocket or air pocket.

Foulants or scalants or growths generally adhere to surfaces from water through direct contact with a solid surface. Water-borne foulants or scalants or growths generally cannot pass through air or other gas to a solid surface. In an instance where water-borne foulants or scalants or growths are somehow capable of passing through air or other gas to a solid surface, it is important to note that mass transfer through said gas may be orders of magnitude less than if water was in direct contact with a solid surface. As a result, water-borne foulants or scalants or growths may have insufficient mass transfer to conduct substantially any or relatively equivalent fouling, scaling, or growth in a gas or air environment relative to an environment of direct solid surface contact with water.

Gas pockets or concave regions or both may increase or decrease stability. Stability may be increased, for example due to ‘suction’ effect or attraction created by a structure with gas-solid interface on one side and solid-water interface on the other side. Stability may be increased by, for example, reducing the center of gravity of the dock by, for example, adding weight to the ‘walls’ of a concave region. By adding weight to the walls of a concave region or near the bottom of the structure, the structure may be less likely to tilt sufficiently to lose gas in a gas pocket, in the event of, for example, a weight imbalance on the structure or a large wave. Gas pockets or concave regions may decrease stability by potentially increasing center of gravity. If a structure is in an environment with significant waves or the potential for rough water, it may be desirable, for example, to incorporate a gyroscopic stabilizer or stabilizing anchors or stabilizing weights or stabilizing earth connected structures to increase stability or minimize tilting.

Gas pockets or concave regions or surface modifications which enable gas pockets may be employed to prevent corrosion or degradation. For example, a corrosion sensitive material or device may be placed in a gas pocket when stored underwater. For example, the propeller of a boat may be surrounded a gas pocket when the propeller or boat is not in use, which may be enabled by encasing or surrounding said propeller with a concave region. For example, underwater hydraulic equipment or underwater trim-tabs may be surrounded a gas pocket when, for example, not in use.

A tube may be placed in the gas pocket or the concave region and gas (for example, including, but not limited to, gases described herein, such as air or nitrogen) may be pumped into the concave regions using said tube and/or a gas pump (which may be connected to said tube). One of the openings of the tube may be placed inside said concave region or below said concave region. The initial pumping of gas into said concave region may enable the formation of a gas pocket in said concave region. After the formation of a gas pocket, additional gas may be pumped into said region to, for example, including, but not limited to, one or more or a combination of the following: expand said gas pocket, to replace gas which may have escaped from said gas pocket, or enable an overflow or spillover of excess gas from said gas pocket and concave region.

Said concave region or gas pocket may be infiltrated with water on, for example, an occasion of a large wave or when a structure is tilted at a significant angle. It may be advantageous for said water contact to be temporary or of as short duration as possible to minimize potential scaling or fouling or corrosion resulting from, for example, water contact. One means of potentially minimizing frequency of water contact may comprise pumping air or other gas into said concave region or cavity using, for example, a tube or pressurized air tank. Said air or other gas may be pumped continuously into said concave region or may be pumped into said concave region only on certain occasions. For example, said certain occasions may comprise when the gas pocket or air pocket is at risk of losing air or at risk of water infiltration into the concave region. For example, said certain occasions may comprise when a structure tilts beyond a specified angle, which may be triggered or measured, for example, using devices for measuring angle change or movement known in the art. For example, said certain occasions may comprise when a portion of the solid surface of said concave region is wetted or at least partially wetted or in contact with water, which may be triggered or measured, for example, using a water or wetting sensor or similar devices known in the art.

It may be desirable for the ‘walls’ to be durable and capable of handling the weight of the dock or multiple docks and resistant to the abuse from other objects or elements. For example, said wall may comprise an a ‘skirt’, for example, wherein the material may be structurally bendable, however can store an air pocket. Said ‘skirt’ may be similar to the ‘skirt’ employed in hovercrafts, although, unlike hovercrafts, the skirt may remain in part or in whole beneath the surface of the water.

An example durable wall comprises a tube connected to the bottom of the dock and attached, for example, near the outside perimeter of the dock bottom and may be surrounding the outside perimeter of the dock. To prevent damage to the ‘walls’, the tube may be collapsible when the dock is being moved. The tube may be inflated or may become more rigid using, for example, including, but not limited to, pneumatic or hydraulic pressure means, such as pneumatic or hydraulic pressure or filling with a pneumatic or hydraulic fluid. Said tube may be connected to the dock in a fashion which prevents air or water from passing through the connection between the dock and the tube ‘walls’.

The present invention and/or elements of the present invention, which may include, but are not limited to, ‘Wall’, gas pocket, concave region, tube, gas pump or air pump, and/or other elements of the embodiments described herein, may be retrofitted onto pre-existing structures or may be an element of new structures.

The present invention may also be applicable to preventing or minimizing foulants or scalants or growths in non-aqueous liquid environments.

Portions of a floating structure may be in contact with water or liquid, for example, which may include solid surfaces outside a concave region or gas pocket. Said solid surfaces in contact with water or liquid may be susceptible to growths, fouling or scaling. It is important to note that a large portion of the solid surface area beneath the surface of the water or liquid may be in contact with a gas pocket, and, as a result, may be unsusceptible or less prone to the formation of growths, fouling or scaling. This may have an effect of significantly reducing or eliminating the formation of growths, fouling or scaling on most of the subsurface surface area of a solid structure. Surfaces in contact with water or liquid may have the formation of growths, fouling or scaling, however it may be important to note 1) side-walls are generally easier to clean/scrub than the bottom/underbody/underbelly of a floating structure; 2) the total amount of the formation of growths, fouling or scaling may be significantly less than if the present invention was not employed; 3) an air curtain may be created which minimizes growth formation on regions not protected by an air pocket by pumping excess air into said cocave region and facilitating the formation of small air bubbles, which may rise along the sides of the structure.

Water may refer to a body of liquid. Said body of liquid may include, but is not limited to, a body of liquid containing at least a portion of water including salt water. Said body of liquid may include, but is not limited to, marine environments, aquatic environments, rivers, lakes, brine pools, frac water, waste water, oil storage, chemical storage, or other liquids environments.

A gas pocket may be trapped or stationary in low turbulence or minimal turbulence or non-turbulent conditions. Non-turbulent conditions may include an environment where the water is calm and non-moving to the naked eye and the structure in said water is also non-moving to the naked eye. Low turbulence or minimal turbulence conditions may include an environment where the water is calm and moving to the naked eye and/or the structure in said water is calm and moving to the naked eye. In a low turbulence environment, although there is discernable movement, the movement of the water or structure is insufficient for more than 10%, or more than 20%, or more than 25%, or more than 30%, or more than 40%, or more than 50% of the gas in the gas pocket to escape from beneath the structure in a 30 second period. It is important to note, said gas escape may not include intentional removal of gas from said gas pocket or the escape of gas through a tube interconnected to said gas pocket.

Some embodiments may be employed to encourage growth formation, such as certain forms of growth. For example, embodiments described herein, such as gas pockets, may be formed in a certain region to kill an invasive species of algae or the eggs of an invasive fish, other potentially harmful water borne life form. For example, a gas pocket may enable localized oxygenation. For example, a gas pocket may enable localized de-oxygenation. For example, a gas pocket may enable localized cooling, which may comprise evaporative cooling, which may increase the longevity of or improve the health of, for example, coral. For example, a gas pocket may enable localized pH adjustment, such as pH increase by CO₂ removal or CO₂ gas stripping.

EXAMPLE EMBODIMENT EQUIPMENT AND DESCRIPTION

Example cost estimates for a dock module:

-   -   Large Dock Module Dimensions: 8 meters long×5 meters wide×¾         meter tall.     -   Contains concave region on bottom of dock which is about 5         meters long, 3 meters wide, and 0.07 meter deep (1.05 cubic         meters total volume of concave region).     -   The below cost estimates assume the dock either was built with a         concave region or retrofitted with a concave region     -   Example Equipment for Embodiment with Grid Electricity Source on         Dock (Material CAPEX):         -   Air pump—for example: 0.38 PSI, 200 Liters per minute, 35             watts, $12         -   ½ inch inside diameter vinyl tubing, 50 ft: $30         -   Low power timer breakout: $13         -   Triple-Axis Gyro Breakout Board (which may also trigger             on/off switch when angle of dock changes): $12.50         -   Total CAPEX: $67.50     -   Example Embodiment with Grid Electricity Source on Dock (Annual         OPEX with On-Off Timer):         -   Assumes Pump Operates on a Timer of 2.5 minutes every 30             minutes or 5 minutes per 1 hour         -   Pump annual electricity consumption: 25.55 kWh         -   Annual electricity cost at $0.10 per kWh: $2.55     -   Example Embodiment with Solar Panel with Battery Setups for         Electricity Source on Dock (CAPEX):         -   Air pump—for example: 0.38 PSI, 200 Liters per minute, 35             watts, $12         -   ½ inch inside diameter vinyl tubing, 50 ft: $30         -   Low power timer breakout: $13         -   Triple-Axis Gyro Breakout Board (which may also trigger             on/off switch when angle of dock changes): $12.50         -   Total CAPEX: $67.50 (if solar panel and battery are expensed             as CAPEX, $108.13 total)     -   Example Embodiment with Solar Panel with Battery Setups for         Electricity Source on Dock (Annual OPEX with On-Off Timer):         -   Assumes Pump Operates on a Timer of 2.5 minutes every 30             minutes or 5 minutes per 1 hour         -   Pump annual electricity consumption: 25.55 kWh         -   Solar panel (determined based on 10% capacity factor, one             100 W solar panel for three dock modules): $28.63 per dock             module         -   264 Wh Battery for 3 dock modules (1.17 days of storage):             $25 per dock module         -   OPEX of Electricity: $0         -   Battery Lifespan: 5-10 years         -   Cost of Battery per Year (assuming 5-year lifespan): $5         -   Solar Panel Lifespan: 25 years         -   Cost of Solar Panel per Year (assuming 25-year lifespan):             $1.15         -   Total Annual OPEX: $6.15             Example Minimum Viable Prototype Materials:     -   1-3 Watt DC Aquarium Air Pump     -   Timer breakout on-off switch which, for example, automatically         turns on the air pump for 20 seconds every 10 minutes         -   Examples:             -   Adafruit TPL5110 Low Power Timer Breakout             -   Mini Timer Time Delay Relay 0.1 Sec to 400 days.     -   Small re-chargeable battery bank, such as 10 Wh battery bank for         smartphone charging     -   Tube to connect air pump and bottom of plastic bin     -   Plastic bin with subtle perimeter lip which creates rectangular         concave region on the plastic container bottom. Alternatively,         an upside-down plastic bin may be employed to simulate the         concave region.     -   Plastic bin to store electronic devices outside the water

EXAMPLE EXEMPLARY EMBODIMENTS

System for fouling and scaling prevention on water structures comprising:

-   -   A structure containing a concave region     -   Wherein said concave region contains a gas pocket     -   Wherein said gas pocket results in a non-contiguous separation         between a water and at least a portion of the surface of said         concave region

System for fouling and scaling prevention on water structures comprising:

-   -   A structure containing a cavity     -   Wherein said cavity contains a gas pocket     -   Wherein said gas pocket results in a non-contiguous separation         between liquid and at least a portion of said cavity

EXAMPLE EXEMPLARY SUB-EMBODIMENTS

-   -   Wherein said non-contiguous separation inhibits the formation of         scalants, foulants, and growths on the solid surfaces in contact         with said region occupied by said gas pocket     -   Wherein a tube with an opening located beneath or inside said         concave region is interconnected to a pressurized gas source     -   Wherein said pressurized gas source may include an air pump, a         gas pump, a pressurized gas line, or a combination thereof     -   Wherein said tube is connected to a valve which allows control         over gas entering or exiting said gas pocket through said tube     -   Wherein at least a portion of the solid surface area in contact         with said gas pocket is separated or not in direct contact with         water for greater than 30%, or greater than 40%, or greater than         50%, or greater than 60%, or greater than 70%, or greater than         80%, or greater than 90%, or greater than 95% of the time said         structure is in said water     -   Wherein said water comprises a body of liquid     -   Wherein said gas pocket displaces liquid     -   Wherein said gas pocket is trapped or stationary in low         turbulence or minimal turbulence or non-turbulent conditions     -   Wherein gas may be pumped into said gas pocket continuously or         semi-continuously or on occasion where gas needs to be         replenished     -   Wherein gas is pumped into said gas pocket in excess of the         volumetric capacity of said cavity or concave region, resulting         in spillover bubbles     -   Wherein said spillover bubbles reduce fouling on solid surface         area not in direct contact with said gas pocket     -   Wherein said spillover bubbles are methodically dispersed along         said solid surface area not in direct contact with said gas         pocket using shape modifications to sections of the structure     -   Wherein said shape modifications may include perforations,         dimples, microscopic modifications, surface morphology, or         macroscopic modifications     -   Wherein the height of said structure over the surface of the         water can be adjusted by increasing or decreasing the volume of         gas in said concave region or cavity     -   Wherein said concave region or cavity is retrofitted onto a         pre-existing structure     -   Wherein said concave region or cavity is an aspect of the shape         of a pre-existing structure     -   Wherein said concave region or cavity is an aspect of the shape         of a new structure     -   Wherein the shape or size or strength or rigidity of said         concave region or cavity may be adjustable     -   Wherein said adjustability may include controlled forming or         collapsing of said concave region or the ‘walls’ of said concave         region     -   Wherein said adjustability may include controlled forming or         collapsing of said concave region or the ‘walls’ of said concave         region using pneumatic or hydraulic means     -   Wherein said adjustability may include controlled volume or         depth or surface area of said concave region     -   Wherein the volume, or shape, or surface area, or depth of said         gas pocket are adjustable     -   Wherein said gas pocket adjustability involves one or more or a         combination of the following: the ability to add or remove gas         from said gas pocket, the ability to change the shape or contour         of said gas pocket or concave region, the ability to adjust the         shape or size of the ‘walls’ of the concave region     -   Wherein said gas pocket contains a non-water liquid in addition         to or instead of a gas     -   Wherein the surface of said gas pocket is hydrophobic or         contains a hydrophobic coating     -   Wherein said gas pocket or concave region or cavity may function         as a diving bell or temporary shelter or storage region     -   Wherein said tube is connected to a check valve which allows gas         (such as air) to enter said tube and/or said concave region,         although does not allow air to be released from said region         Prior-Art—Incorporated Herein by Reference     -   Physically Removal of the Barnacles:         https://www.scubadubacorp.com/Dockcleaning.htm     -   Air bubble curtain—air bubbles are sparged over hull:         https://www.tandfonline.com/doi/pdf/10.1080/20464177.2009.11020214     -   https://www.researchgate.net/profile/Sandra_Shumway/publication/44684741_The_use_of_aeration_as_a_simple_and_environmentally_sound_means_to_prevent_biofouling/links/0c96051ffe80269766000000.pdf     -   https://patents.google.com/patent/US20050087117A1/en

FIGURE KEY

-   -   ‘1’ or ‘(1)’: Top section of a floating platform or dock     -   ‘2’ or ‘(2)’: Floats or pontoons, bottom section of a floating         platform or dock     -   ‘3’ or ‘(3)’: Gas or air pocket, which may be in the concave         region on the underside or bottom of ‘2’     -   ‘4’ or ‘(4)’: Liquid body, such as a body of water or oil     -   ‘5’ or ‘(5)’: Extended walls, which may extend beyond the         vertical depth of the air pocket     -   ‘6’ or ‘(6)’: Air or gas bubble curtain up the side walls of ‘2’         in contact with water. ‘6’ may result from gas being pumped into         a concave region, and the gas pocket exceeding the volume of the         concave region's gas capacity. The bubble curtain may be         facilitated by perforations or dimples in the side walls. A         bubble curtain may reduce growth formation on surfaces not in         contact with the gas pocket.     -   ‘7’ or ‘(7)’: Air or gas pump connected to tubing (lines with         arrows). Tubing may interconnect said gas or air pumped by said         pump with the concave region.

FIG. 1: An example dock with a concave region ‘gas pocket’ (3′) on the bottom of each float or pontoon. The gas pocket may enable a large portion of the surface area on the bottom of the dock, or the surface area of the dock in contact with the air pocket, to have minimal or no levels of foulants, scalants, or growths.

FIG. 2: An example dock with a concave region ‘gas pocket’ (3′) on the bottom of each float or pontoon. A tube may be placed beneath or connected to bottom of dock. Air or other gas may be pumped into the tube, which directs gas into the gas pocket. If the volume of gas exceeds the volume of the concave region or cavity, bubbles may travel up side of dock, which may, if desired, form a bubble curtain along the side of the dock (6′). Said bubbled curtain may be facilitated, for example, by placing dimples or perforations in the ‘walls’ of concave region. Dimples or perforations may be located near the bottom of the vertical depth of said ‘walls’ of the concave region. Said bubble curtain may be desirable to minimize fouling, scaling, and growths outside of the gas pocket. If a continuous bubble curtain is desirable, a continuous flow of pumped air may be required.

FIG. 3: An example embodiment with extended ‘walls’, which may be employed to prevent air or gas losses in the event of, for example, waves, turbulent water, or a significant change in the angle of the dock. Extended walls may extend to a depth beyond the depth of the air pocket. Extended walls may be weighted, if desired, to reduce center of gravity. It may be desirable to prevent the air pocket from extending to the full depth of the extended walls (for example: to ensure the dock is stable), in which case it may be desirable to include small perforations in certain parts of the extended walls. Air or other gas may need to be pumped into the air pocket less frequently or on fewer occasions in embodiments with extended walls.

FIG. 4: An example embodiment where changing the volume of gas in a gas pocket adjusts the height above the liquid surface and/or angle of a floating structure, such as a dock. FIG. 4 may show the height of a dock above the surface of water being increased by pumping air into two concave regions, increasing the volume of an air pocket and displacing water from the concave regions. The present embodiment may be advantageous for increasing or decreasing the height or reducing the draft of a dock. Advantageously, relatively little energy may be required to increase the height of the dock due to, for example, the potentially low air pressure in the concave region due to, for example, the relatively small head height. Advantageously, no moving parts are required to be in contact with the liquid.

FIG. 5: An example embodiment where changing the volume of gas in a gas pocket adjusts the height above the liquid surface and/or angle of a floating structure, such as a dock. FIG. 5 may show the height of a dock above the surface of water being decreased by releasing air from concave regions, increasing the volume of an air pocket and displacing water from the concave regions. The present embodiment may be advantageous for increasing or decreasing the height or reducing the draft of a dock.

Second Description of Embodiments

Example Energy Storage Embodiments Overview:

Introduced are systems, and methods for energy storage and/or simultaneous oil or chemical storage. In some embodiments, energy is stored via a hydrostatic pressure difference between one or more insoluble or low solubility fluids, which may be driven by a density difference between the one or more fluids. The technology may employ the depth of water bodies to, for example, enable this hydrostatic pressure. An embodiment may comprise, for example, a relatively high density liquid, and a relatively low density liquid or fluid, which may have a lower density than the relatively high density liquid. The end-to-end technology may be a closed system or may be at least closed beneath the surface of the water body. In some embodiments, all or almost all moving parts above the surface of the water body, such as ocean or lake, or, advantageously, not have moving parts, or not have essential moving parts or not have relatively costly moving parts, under water or deep under water, or no moving parts at a depth greater than 250 ft under water, or no moving parts at a depth greater than 1000 ft under water. It may be beneficial for the system to be a closed system, wherein the internal fluids, for example high density and low density liquids, are in direct contact with each other. The internal fluids may be separate from or substantially not in contact with the surrounding water body. The water in the water body may simply be employed to ensure pressure, for example liquid pressure, is in equilibrium between the inside fluids and surrounding or external water body. An equilibrium in pressure between the outside and inside of the vessel may enable, for example, the use of lower cost materials, as, for example, at least a portion of the materials may not require resistance to pressure differences or substantial differences. Energy may be stored in the hydrostatic pressure difference between the media (for example: liquids) inside the vessel, for example, wherein one or more media have a higher hydrostatic pressure than another one or more media. Difference in hydrostatic pressure may be driven by the difference in hydrostatic pressure of liquids of difference densities at the same hydraulic head height. An embodiment may comprise media comprising two or more immiscible or low solubility liquids with different densities. The difference in density between two or more liquids at the same or similar height may drive the hydrostatic pressure difference. Advantageously, the process may operate with greater than 70% or 80% round-trip efficiency due to the incompressibility of liquids and high efficiency of hydroelectric generators.

Embodiments may employ liquids, solids, gases, supercritical fluids or other media phases. One or more phases may be advantageously employed, for example, because said integrated system may be a closed system. For example, in a closed system, contamination with the surrounding water body may not be a challenge, unless, for example, there is a leak.

In one embodiment, liquid storage of a higher density liquid (such as water) and liquid storage of a lower density liquid (such butane) are placed at a relatively higher head height than a separate liquid-liquid interface vessel or vessels. Said relatively higher head height may be including, but not limited to, one or more of a combination thereof: located lesser depth in the surface of a water body, at the surface of a water body, above the surface of a water body, floating on the surface of a water body, located on land adjacent to a water body, or located on another water body, or located on land. It may be desirable for the higher density liquid to have the same or similar density as the surrounding water body at the same depth. For example, if the pipe or container containing the high density and low density liquids are in ocean, the higher density liquid may comprise a liquid of the same or similar or relatively close density as the surrounding water body or other surrounding media. Alternatively, the higher density liquid may significantly differ in density from the surrounding water body or other surrounding media, as in such an embodiment, pressure difference resistant materials may be required. Separate liquid-liquid interface storage vessel or vessels may be located at a lower head height than the liquid storage. Said liquid-liquid interface storage vessel or vessels may be connected to the higher head height liquid storage vessel or vessels using one or more tubes. Tubes may be employed to transport the lower density liquid or the higher density liquid or a combination thereof. One or more tubes may be connected to one or more valves or pumps or sealed connecting joints. For example, the lower density liquid may be connected to liquid tube or tubes, which may be connected to one or more pumps or generators or connected to low density liquid storage or a combination thereof. For example, the higher density liquid may be connected to liquid tube or tubes, which may be connected to one or more pumps or generators or connected to higher density liquid storage or a combination thereof.

Storing energy may involve, for example, pumping the lower density liquid into a tube or tubes, displacing at least a portion of the higher density liquid out of the tube or tubes and underwater vessel or vessels into the higher density liquid storage or, alternatively, displacing the higher density liquid into the surrounding water body. Energy may be stored energy due to the difference in hydrostatic pressure between the low-density liquid and high density liquid at the same hydraulic head height—for example, as the low density is pumped into the tubing or storage vessel, it is overcoming the hydrostatic pressure of the higher density liquid, developing a hydraulic head. When the storage device stops charging, a valve may be employed to prevent the one or more liquids from undesirably reversing flow direction.

A check valve may be employed during pumping operation to prevent the low-density liquid from reversing pumping direction. Energy storage time-period may indefinite if there are no leaks. During discharge, one or more valves may open, enabling the pressurized low-density liquid to be at least partially displaced and enable said low density liquid to power a generator. Valves, pumps, generators, and other moving parts may be located at the surface or just below the surface, or on land, or a combination thereof as this may reduce capital, operational, and/or maintenance costs.

In another embodiment, the process may be an open system, wherein the higher density fluid is comprises the fluid in one or more liquid or water bodies, such as, for example, water or salt water or oil or relatively inexpensive liquid. For charging, the low density liquid may be pumped into one or more vessels, displacing the higher density water or liquid in the vessel. The process may contaminate the water in the bay, although this may be minimized by, including, but not limited to, minimizing mixing, preventing the contaminant liquid level, for example the low density liquid level, from approaching or surpassing the edge of the vessel, using a low solubility or insoluble combination of liquids or media, using a non-hazardous or inexpensive low density liquid, or a combination thereof. In the present embodiment, a high density liquid storage vessel may be unnecessary, potentially reducing capital cost and complexity. A version of the present embodiment may comprise an upside down barrel with a tube opening on the inside of the closed, upward facing side of the barrel and a port open to the surrounding liquid body (for example, water body or ocean or lake) on the bottom facing side of the barrel. A version of the present embodiment may comprise an upside down barrel with a tube connected to a liquid tight port connected to upward facing side of the barrel and a port open to the surrounding liquid body (for example, water body or ocean or lake) on the bottom facing side of the barrel. A version of the present embodiment may not contain any liquid tight ports—a tube may be fed into the open side of the up-side-down vessel or barrel and attached to the bottom (inside of top of barrel because up-side-down) of the inside of the vessel or barrel. Advantages of said alternative embodiment include, but are not limited to, a simplified construction, higher pressure resistance, lower opportunity for leak or contamination, and low cost. One or more vessels or barrels may be further connected to a weight or anchor and the upper region of the barrel may be connected to floatation to maintain the one or more vessels or barrels in the desired position (for example, the upside-down position). One or more tubes may be further connected to a pump or generator, which may be further, connected to one or more low density fluid storage vessels. Said one or more lower density liquids (or other fluid, such as a gas) storage vessels may be located at a higher head height, for example, near the surface, at the surface, or above the surface of the water body. During charging, the lower density liquid (or other fluid, such as a gas) may be pumped into the vessel, displacing the higher density liquid. During discharging, low density liquid may be pumped into the vessel, displacing the higher density liquid.

Pressure of Low Density Liquid:

The pressure of the low density liquid when the liquid is forced to displace higher density liquid, as is the case when energy is stored, may be at a higher pressure than the surrounding water body, wherein the pressure difference between the low density liquid and the surrounding water body increases with decreasing depth. At the interface between the lower and higher density liquids, the pressure of the two liquids may be equal or close to equal. As the depth of the lower density liquid decreases (or the higher the low density liquid is above the liquid-liquid interface), the greater the lower density liquid deviates in pressure from the higher density liquid or the greater the net pressure of the low density liquid. As a result, the tube or other vessel transporting the lower density liquid across depths or head heights may require pressure resistance, the pressure resistance requirement may increase with decreasing depth (or greater hydraulic height from the liquid-liquid interface or deepest point). The point of the pump or generation may comprise the highest pressure in the embodiment. One way of describing this phenomenon is:

-   -   If an open tube is placed vertically in a water body, the water         inside the tube, although separated, is predominately at the         same pressure as the surrounding water body at any given depth         because the water pressure applied by the water inside the tube         above a given point in the tube is the same as the water         surrounding the tube. Similarly, when a liquid of different         density, such as a lower or higher density, is placed in a         closed bottom vessel in open air, the pressure of the liquid at         any given point may be equivalent to the liquid pressure applied         by the liquid above a point in the liquid. At the same height or         depth, a liquid of lower density may have a significantly lower         gravitationally derived pressure than a liquid of higher         density. When a lower density liquid is displacing a higher         density liquid (for example, due to the application of an         outside force) in a location experiencing gravity, the net         pressure or pressure difference experienced by the lower density         liquid at any given height above the liquid-liquid interface or         deepest point of the low density liquid is:         P _(Net) =P _(HD) −P _(LD)

Wherein:

-   -   ‘P_(Net)’ may be the Net Pressure of Lower Density Liquid at a         Given Height above the Lowest Depth of the Lower Density Liquid         or Liquid-Liquid Interface     -   ‘P_(HD)’ may be the Gravitational Pressure Head of Higher         Density Liquid at the Height Above Lowest Depth of Low Density         Liquid or Liquid-Liquid Interface     -   ‘P_(LD)’ may be the Gravitational Pressure Head of Lower Density         Liquid at Height Above Lowest Depth of Low Density Liquid or         Liquid-Liquid Interface

FIG. 6: FIG. 6 shows a simplified setup of an embodiment employing a lower density liquid and a higher density liquid. The two boxes with black text are the higher head height liquid storage vessels. The higher head height liquid storage region is connected via tubes or pipes to one or more separate storage vessels. In FIG. 6, the tubes are connected to a single storage vessel at a head height below the surface of the liquid body (such as a water body) and located at a head height below the higher head height liquid storage vessels, which may be referred to as the lower head height storage vessel. The higher density liquid tube or pipe is connected to one or more ports at the bottom of the lower head height storage vessel. The lower density liquid tube or pipe is connected to one or more ports at the top of the lower head height storage vessel. It is important to note the location of placement of ports on the lower head height storage vessel may not be of importance, and ports may be placed, in, including, but not limited to: next to each other, across from each other vertically, across from each other horizontally, placed randomly, or in another configuration or in a combination thereof. It may be important for the ports to be liquid tight. An exception may be, for example, if the heavy liquid port is open to the surrounding water bay, potentially eliminating the need for a liquid tight port for the higher density liquid and potentially eliminating the need for a high density liquid pipe or storage vessel. The region inside the lower head height vessel where the higher density liquid and lower density liquid meet may be referred to as the fluid-fluid or liquid-liquid interface. The liquids may be contacted directly, in which case it may be desirable for the liquids to be immiscible. The liquids may also be spaced or separated or constitute non-contiguous liquids by a separator or drum, including, but not limited to, a drum or floating drum. If a floating drum is employed to separate the higher density liquid from the lower density liquid, it may be desirable for the floating drum to be of lower density than the higher density liquid and higher density than the lower density liquid. A liquid-liquid separator or drum may be employed, for example, to reduce liquid-liquid mixing (especially important for soluble liquids) or, in the case where open water is the high density liquid higher density liquid, reduce environmental contamination. Energy is storage by pumping the lower density liquid into the lower density liquid tube or pipe, which may displace the higher density liquid from the lower head height storage vessel. Stored energy may be released by enabling the displaced water to enter the lower head height vessel, which may displace the lower head height liquid and generate electricity. In the configuration shown in FIG. 1, the pump/generator is shown connected to the lower density liquid pipe or tube, which may enable higher pumping efficiency. Pump may be above the water surface, enabling no moving parts to be under water. The lower density liquid may be under pressure during charging and discharging.

A pump/generator may be connected to the higher density liquid. One potential challenge of pumping the higher density liquid directly is charging may require the formation of a partial vacuum, which may be less efficient and, even in the case of a pure vacuum, may not be enough driving force to remove sufficient higher density liquid from the lower head height vessel. It may be desirable for the pump or generator to be beneath the water line, for example, if the pump or generator is directly in contact or pumping the higher density liquid.

Liquid storage regions may comprise tanks or reservoirs storing the lower density liquid or higher density liquid. Substantially immiscible or insoluble may mean a liquid which is less than 50 weight percent (wt %), or less than 40 wt %, or less than 30 wt %, or less than 20 w % soluble in the other liquid.

It may be advantageous for the higher density liquid storage region to be beneath the water line or at the same or similar or lower depth than the liquid-liquid interface or lowest point of the lower density liquid. This may be advantageous, for example, if the higher density liquid has the same density as the liquid body, such as water body, surrounding the energy storage device. The higher density liquid storage region may comprise, for example, a bladder-like storage device in pressure equilibrium with the surrounding liquid body, such as water body. The higher density liquid storage region may comprise, for example, a storage device with a floating or movable roof in pressure equilibrium with the surrounding liquid body, such as water body.

The lower head height vessel may be pressure difference resistant. The pressure resistance required by the lower head height vessel may increase with vertical distance from the liquid-liquid interface or lowest point of the lower density liquid. It may be advantageous to minimize the vertical height of the vessel, minimizing the pressure difference experienced by the lower head height vessel compared. This may transition more or most of the lower density liquid pressure difference to the pipe/tube. It may be advantageous to progressively increase the reinforcement of the lower head height vessel with increasing vertical distance from the liquid-liquid interface or the lowest point of the lower density liquid. For example, the structure of progressively increasing the reinforcement of the lower head height vessel may be similar to water towers, wherein the vessel is progressively more pressurize resistant and reinforced with higher hydrostatic pressure.

The higher density liquid storage and lower density liquid storage may be, for example, located beneath the surface, floating on the surface, or on land. In some embodiments, the higher density liquid storage may comprise the surrounding water body. In some embodiments, the higher density liquid storage may be in a different location than the lower density liquid storage. For example, the higher density liquid storage may be a bladder like expandable and contractible volume storage region beneath the water body surface, while the lower density liquid storage region may be located on land.

The energy storage device may undergo charging or discharging at any point in storage capacity. For example, if the device is at least a portion charged, it may be discharged. For example, if the device is at least a portion discharged, it may be charged. For example, if the device is fully charged, it may not have the capacity to further charge. For example, if the device is fully discharged, it may not have the capacity to further discharge.

Example Step by Step Description:

FIG. 7: Step 1: FIG. 7 may show an energy storage device undergoing charging. A liquid pump may pressurize and pump the Lower Density Liquid (LDL) into a pipe connected to the lower head height storage region, which may allow the LDL to displace the higher density liquid (HDL) in the lower head height storage. As HDL is displaced by the LDL, gravitation potential energy may be stored. In FIG. 7, HDL may be shown being transferred it to an HDL storage region above the lower head height storage region. The HDL storage region, for example, if it comprises a fluid in equilibrium with the hydrostatic pressure of the surrounding liquid or of the same density as the surround liquid, may be located elsewhere, for example, beneath the surface of the liquid body, or at the same height or depth as the lower head region, or below the depth of the liquid-liquid interface. The pump or pumps may be powered by work, for example, electricity, hydraulic pressure, or mechanical work.

The LDL may a volatile liquid (such as propane or butane) and the LDL storage region may be closed. Regardless of whether the LDL is volatile, the LDL storage region may be closed to outside air. If the LDL is sufficiently volatile, the headspace gases in the LDL may comprise the LDL in the gas phase. If the LDL has a sufficiently high partial pressure (for example: propane or butane), the LDL storage region may be pressure resistant and comply with the appropriate safety precautions.

The HDL may be a volatile liquid. The HDL may comprise water. It may be desirable for the HDL storage region to not be open outside air, as biofouling agents and other contaminants may enter. Alternatively, the headspace of the HDL storage region may comprise, for example, filtered or treated air.

FIG. 8: Step 2: FIG. 8 may show an energy storage device at a relatively charged state. At a charged, or discharge, or when charged, or when at a steady state, a check valve may be employed to prevent liquid from flowing into the LDL tank.

It may not be advantageous to have LDL enter the higher density liquid region, which may occur, for example, during overcharging if the HDL storage region is located at a higher height relative to the LDL. If this were to occur, for example, the LDL may float to the surface of the HDL storage region if the HDL storage region is at a higher height relative to the LDL liquid-liquid interface. This may be remediated, for example, by removing the LDL from the HDL using, for example, one or more or a combination of the following: decanting, cyclone, coalescer, filter, or other means of phase or liquid-liquid separations. If the LDL forms a gas phase at the conditions in the HDL storage region, the LDL may be separated by, for example, including, but not limited to, one or more or a combination of the following: removing LDL gas from the headspace, compression of headspace gases, cooling headspace gases, gas separation methods, pressure swing adsorption, pressure swing absorption, membrane, distillation, combustion, absorption, or adsorption.

FIG. 9: Step 3: FIG. 9 may show an energy storage device discharging. HDL may displace LDL in the subsurface storage region, which may result in high pressure LDL passing through a generator, generating electricity, and entering, for example, an LDL storage tank.

FIG. 10: Step 4: FIG. 10 may show an energy storage device at a relatively discharged state. At a discharged or charged or when charged or when at a steady state, a check valve may be employed to prevent liquid from flowing into the LDL tank.

FIG. 11: FIG. 11 may show an example embodiment where the LDL and/or HDL storage regions at a higher head height or above the surface are located on a platform or a floating platform. If desired, the only direct interconnected between the energy storage device and land may be a medium for transporting electricity, such as an electric cable.

FIG. 12: FIG. 12 may show an example embodiment where the LDL and/or HDL storage regions at a higher head height or above the surface are located on land, such as on the shore or on an island.

FIG. 13: FIG. 13 may show an example embodiment where multiple subsurface storage regions are employed for energy storage. If there is more than one subsurface storage region, the subsurface storage regions may be interconnected, which may minimize the number of pipes between the higher head height storage region or regions and the lower head height or subsurface storage region or regions.

Example Installation of an Example Embodiment:

-   -   1. Connect tubes (lower density liquid tube and higher density         liquid tube) to the two ports of a liquid-tight vessel. Tubes         may be wrapped in a roll or in another storage configuration.         -   a. The location of the ports may be of importance, and may             be located, for example, to minimize mixing. For example,             ports may be located near the top of the vessel for the             low-density liquid tube connection and near the bottom of             the vessel for the higher density liquid tube.         -   b. Tubes may be connected to one or more rolls of tubing         -   c. Tubes or vessels may require withstanding pressure,             although in some embodiments only the tube transporting the             lower density liquid must withstand substantial pressure             differences.     -   2. Fill the vessel or tubes or both with a liquid at the same or         similar density as surrounding water body (for example: if         ocean, same density as ocean water, may be salt water or an         aqueous solution containing a dense organic additive, such as         glycerol or ethylene glycol or propylene glycol. It may be         desirable for the liquid to not comprise bio-foulants, scaling         agents, or corrosion or degradation causing agents).         Alternatively, the liquid may comprise bio-foulants, scaling         agents, or corrosion or degradation causing agents, for example         raw ocean water or lake water or raw oil storage liquid or raw         waste water or other liquid. The liquid filling the vessel or         tubes or both in the present step may be considered the higher         density liquid.     -   3. Attach tubes to their desired storage tank and generator/pump     -   4. To ensure the vessel remains in the desired position (for         example, such as upright) and prevent tangling of tubes, the         implementation may involve attaching one or more weights or         anchors to near the bottom of the vessel and one or more buoyant         floats to near the top of the vessel. The float or near top of         the vessel or combination thereof may be further attached to a         line, which may be connected by a connector comprising a         detachable mechanism, such as clip, or remotely detachable clip.     -   5. Allow vessel to sink to a desirable depth, for example, near         or at the bottom of a water body. Unravel the tubes and lines         (for example: the float line and guide line) as the vessel         sinks.     -   6. When the vessel reaches its desired depth (for example: the         depth at which the weight or anchor reaches the bottom) the         guide line may be detached or may be attached to a float         specifying the location.     -   7. To charge, pump low density liquid into the liquid tubes or         vessels, displacing the higher density liquid, which travels         through an adjacent tube into a storage vessel. During charging,         the low-density liquid may displace the higher density liquid in         the tube or in the vessel or in a combination thereof.     -   8. To discharge, open valve, allowing pressurized low-density         liquid (for example: from step 8) to the generator (which may         be, for example, a separate generator or may be a pump that can         reversibly be used as a generator).         Potential Benefits of Energy Storage Technology Described         Herein:     -   >80% round trip efficiency         -   Liquid pump and generator achieves high efficiency and low             thermodynamic losses     -   Unlimited available land area (sits at bottom of water body or         ocean)     -   Unlimited storage time     -   Unlimited charge/discharge cycles         -   No moving parts in ocean         -   No degradation or corrosion         -   Reagents do not contact with ocean (water body, such as             ocean, is simply used to create depth/head height with same             surrounding hydrostatic pressure)         -   Unaffected by marine or water body growths (e.g. barnacles,             slimes)             -   Entirely closed system     -   Cost per kWh—Butane costs ˜$300 per m³ liquid     -   Energy density (at 1000 m—1 m³ of butane—water is about 1 kWh of         electricity)     -   No environmental impact         -   Closed system         -   Non-toxic reagents (if a leak were to occur)     -   Abundant, Non-toxic, Non-volatile reagents and building         materials     -   Simple, low cost construction         -   Hydrostatic pressure inside technology may be the same as             its surroundings. Enables use of low cost, less pressure             resistant materials in construction. (Note: Tube connected             to low density liquid may require higher pressure             resistance)         -   No moving parts in water         -   Embodiment may comprise three tanks (two on surface, one on             ocean floor), two pipes and one pump/generator

It may be desirable for the high density liquid (HDL) to have the same density as the surrounding water body liquid. This may enable similar hydrostatic pressure inside the vessel(s) and/or pipes as surrounding the vessel(s) and/or pipes, enabling the potential use of lower cost, less pressure resistant materials.

To maximize the energy density of the introduced storage device, potentially desirable characteristics, include, but are not limited to, large net density difference (i.e. [density of high density liquid]−[density of ‘low density liquid’]) and low pressure or temperature driven liquid compression (e.g. water minimally compresses under high pressure). An example of this includes, but is not limited to, propane (LDL) and water (HDL)

To enable effective functionality of the introduced storage device, potentially desirable characteristics, include, but are not limited to, two or more reagents that are substantially insoluble or immiscible. It may be desirable for the high density liquid and low density liquid to be substantially insoluble or immiscible in each other.

To minimize capital cost, potentially desirable characteristics, include, but are not limited to, low cost reagents, low density for low density liquid, and/or low corrosion or non-corrosive reagents. For example, butane and propane are low cost and liquid at higher pressure operation.

To minimize capital cost, potentially desirable characteristics, include, but are not limited to, employing materials that are compatible with the reagents inside the integrated process. For example, polypropylene or HDPE is inexpensive, abundant, corrosion resistant, and compatible with water, seawater, butane and propane.

The energy storage device may also be a means of storing hydrocarbon liquids or chemicals or volatile hydrocarbons. For example, the LDL storage region and lower head height storage region may comprise storage for hydrocarbons, such as, for example, including, but not limited to, crude oil, gasoline, diesel, kerosene, ethane, propane, butane, hexane, octane, cyclopropane, or decane, or a combination thereof. Hydrocarbon liquids are stored in small, medium, or large quantities before they are used or transported in various applications, such as polymer production, fuel, or other uses. By employing the energy storage device as a simultaneous relatively low density liquid storage device, the capital expense of the hydrocarbon liquids may be avoided. For example, oil & gas companies, hydrocarbon transport companies, oil traders, commodity traders, chemical companies, and other users of hydrocarbons or other relatively low density liquids may employ the present energy storage device as a hydrocarbon liquid storage device. For example, the owners or operators of the energy storage device may be compensated for the storage or service or storing the relatively low density liquids. Although the relatively low density liquids may be purchased, in the present embodiment, the relatively low density liquids may advantageously not be purchased by the owner or operator of the energy storage device. Alternatively, the owner or operator of the energy storage device may be compensated for properly storing the relatively low density liquids. This may eliminate the need to pay the capital expense of purchasing the hydrocarbon liquids, while also developing a new revenue source for storing the hydrocarbon liquids.

High density liquid may comprise a higher density liquid with limited solubility in water, such as propylene carbonate (density of ˜1.2 g/cm3) or ethylene glycol diacetate (density of ˜1.128 g/cm3). With said higher density liquid with limited solubility in water, water may be employed as a low density liquid. Said higher density liquids may be low cost, non-volatile, and relatively non-toxic, enabling their use in large volumes in aquatic or marine environments. Aquatic and marine are used interchangeably herein.

Ridged storage regions or containers may be employed for the storage region or regions located beneath the surface of the water. Said storage regions may include, but are not limited to, storage containers presently employed to store crude oil or chemicals beneath the surface of the ocean or other water body. Storage regions, including non-ridged or ridged storage regions or containers, may be located outside the water or liquid body. Alternatively or additionally, the storage regions may be located in strategic oil reserves, oil storage, natural gas storage, liquids storage, saline aquifers, geological formations, or oil & gas wells. It may be desirable for one or more storage regions experiencing greater than atmospheric pressure hydrostatic pressure to be in an environment where the surroundings exert a similar or supplemental pressure to minimize the strength requirements and potential cost of a storage region or container. In the case of a solid surroundings, such as a geological formation, such as a salt cavern, the geological formation or artificially constructed geological formation may function to contain or store said liquids directly and may function as a storage region on its own.

EXAMPLE EXEMPLARY EMBODIMENTS

-   -   An energy storage device comprising:         -   Two or more storage regions         -   Wherein at least one storage region is at a greater pressure             than another storage region         -   Wherein energy is stored using the difference in pressure             between a lower density liquid and a higher density liquid             at the same head height or depth     -   An energy storage device comprising:         -   Two or more storage regions         -   Wherein at least one storage region is at a greater pressure             than another storage region         -   Wherein said energy storage device is charged by pumping a             relatively low density liquid into a storage region to             displace a relatively higher density liquid         -   Wherein said energy storage device is discharged by allowing             a relatively higher density liquid to displace a relatively             lower density liquid and allowing the flow of said lower             density liquid to power a generator or hydraulic turbine     -   A subsea oil or chemicals storage facility which simultaneously         functions as a large-scale energy storage device comprising:         -   Two or more storage regions         -   Wherein at least one storage region is at a greater pressure             than another storage region         -   Wherein energy is stored using the difference in pressure             between a lower density liquid and a higher density liquid             at the same head height or depth     -   A subsea oil or chemicals storage facility which simultaneously         functions as a large-scale energy storage device comprising:         -   Two or more storage regions         -   Wherein at least one storage region is at a greater pressure             than another storage region         -   Wherein said energy storage device is charged by pumping a             relatively low density liquid into a storage region to             displace a relatively higher density liquid         -   Wherein said energy storage device is discharged by allowing             a relatively higher density liquid to displace a relatively             lower density liquid and allowing the flow of said lower             density liquid to power a generator or hydraulic turbine     -   A process for storing energy/electricity while simultaneously         storing natural gas comprising         -   Storing natural gas in gas bags or a storage region beneath             the surface of a water body         -   Storing electricity compressing or pumping natural gas into             said gas bag or storage region, which may expand the volume             of said storage region         -   Discharging or generating electricity by allowing said             natural gas leave said gas bag or storage region and pass             through a generator or turbine         -   Wherein said storage region is connected to a natural gas             pipeline or LNG facility or natural gas facility on the             surface through one or more tubes or pipes

EXAMPLE EXEMPLARY SUB-EMBODIMENTS

-   -   Wherein energy is stored in the displacement of a higher density         liquid using a lower density liquid under conditions where the         pressure head due to gravity of the higher density liquid         exceeds the gravitational pressure head of the lower density         liquid     -   Wherein the pump may function as a generator reversibly     -   Wherein one storage region is located beneath the surface of a         water body and another storage region is located near or above         the surface of a water body     -   Wherein said storage regions function as oil or chemicals         storage     -   Wherein said said low density liquid or high density liquid or         both are the oil or chemicals requiring storage     -   Wherein the storage region beneath the surface of the water body         constitutes a higher pressure, lower head height storage region,         while the storage region above the surface of a water body         constitutes a lower pressure, higher head height region     -   Wherein the pump or generator is located near or above the         surface of a water body     -   Wherein said storage region beneath the surface of a water body         contains a concave region with an opening near the bottom of         said concave region open to the surrounding water body     -   Wherein a drum or separator separates or is located between the         lower density liquid and the water from the surrounding water         body     -   Wherein said storage region beneath the surface of a water body         comprises an expandable or contractible or flexible structure,         such as a bladder or bag or balloon, which may expand and fill         with low density liquid during charging and collapse or         contracted or empty during discharging     -   Wherein said storage region comprising an expandable or         contractible or flexible structure may displace water around         said storage region     -   Wherein the high density liquid constitutes water or water body         surrounding a storage region     -   Wherein said storage region beneath the surface of the water         body may be anchored or tethered to the ground near the bottom         of said water body     -   Wherein the pump or generator is in contact with the low-density         liquid     -   Wherein the pump or generator is in contact with the         high-density liquid     -   Wherein the pump or generator is in located beneath the surface         of the water     -   Wherein the pump or generator is in contact with the         high-density liquid and located near the lower head height,         higher pressure storage region     -   Wherein, during charging, the high-density liquid is pumped out         of a storage region and the lower density liquid replaces the         higher density liquid     -   Wherein one or more storage regions is employed for the storage         of one or more chemicals     -   Wherein the low-density liquid or the high density liquid or a         both comprise the chemicals being stored     -   Wherein low-density liquid or high density liquid or both may be         added or removed from said system     -   Wherein said storage facility/energy storage device is located         near an oil platform or chemicals facility     -   Wherein a processing unit is employed to separate out residual         high density liquid from low density liquid or vise versa before         said liquid or liquids are used or transported after removal         from said storage region     -   Wherein the storage units may be employed for storage of oil or         chemicals when excess storage is required     -   Wherein the storage units may contain more of, or filled with,         or almost fully filled with, or filled with more of low-density         liquid to temporarily or semi-permanently or permanently         employed for oil or chemical storage, for example, in the event         said storage is needed     -   Wherein the storage units may contain more of, or filled with,         or almost fully filled with, or filled with more of high-density         liquid to temporarily or semi-permanently or permanently         employed for oil or chemical storage, for example, in the event         said storage is needed     -   Wherein the system may be optimized to prioritize or balance         energy storage or oil storage or chemical storage or a         combination thereof depending on, for example, including, but         not limited to, one or more or a combination of the following:         -   The amount of chemicals or oil requiring storage         -   The market rate/price for chemical or oil storage         -   The market rate/price of energy storage in the electricity             grid         -   The arbitrage value available for energy storage         -   The arbitrage value available for chemical storage     -   Wherein the low density liquid is a low density fluid     -   Wherein said low density fluid comprises a gas     -   Wherein said low density fluid or gas may comprise natural gas     -   Wherein said natural gas may be employed in said system for         energy generation and oil natural gas storage     -   Wherein natural gas may be stored in the form of compressed         natural gas (CNG) or liquid natural gas (LNG)     -   Wherein said storage region is connected to a natural gas         pipeline or LNG facility or natural gas facility on the surface         through one or more tubes or pipes     -   A process for storing energy/electricity while simultaneously         storing natural gas comprising         -   Storing natural gas in gas bags or a storage region beneath             the surface of a water body         -   Storing electricity compressing or pumping natural gas into             said gas bag or storage region, which may expand the volume             of said storage region         -   Discharging or generating electricity by allowing said             natural gas leave said gas bag or storage region and pass             through a generator or turbine         -   Wherein said storage region is connected to a natural gas             pipeline or LNG facility or natural gas facility on the             surface through one or more tubes or pipes

Lower head height, higher pressure storage region may be equivalent to the storage region beneath the surface of a water body

Energy Density (Butane—Water):

Potential Energy Head Height (Wh per m³) (m) (One Cycle) 1 1.09 2 2.18 3 3.27 4 4.36 5 5.45 6 6.54 7 7.63 8 8.72 9 9.81 10 10.9 100 109 1000 1090 Liquid Densities

The table below shows the densities of various example liquids, which may be employed in the technology introduced herein.

Temperature Density - t - - ρ - Liquid (° C.) (kg/m³) Acetic Acid 25 1049 Acetone 25 784.6 Acetonitrile 20 782 Alcohol, ethyl (ethanol) 25 785.1 Alcohol, methyl (methanol) 25 786.5 Alcohol, propyl 25 800.0 Ammonia (aqua) 25 823.5 Aniline 25 1019 Automobile oils 15 880-940 Beer (varies) 10 1010 Benzene 25 873.8 Benzil 15 1230 Brine 15 1230 Bromine 25 3120 Butyric Acid 20 959 Butane 25 599 n-Butyl Acetate 20 880 n-Butyl Alcohol 20 810 n-Butylhloride 20 886 Caproic acid 25 921 Carbolic acid (phenol) 15 956 Carbon disulfide 25 1261 Carbon tetrachloride 25 1584 Carene 25 857 Castor oil 25 956.1 Chloride 25 1560 Chlorobenzene 20 1106 Chloroform 20 1489 Chloroform 25 1465 Citric acid, 50% aqueous solution 15 1220 Coconut oil 15 924 Cotton seed oil 15 926 Cresol 25 1024 Creosote 15 1067 Crude oil, 48° API 60° F. 790 Crude oil, 40° API 60° F. 825 Crude oil, 35.6° API 60° F. 847 Crude oil, 32.6° API 60° F. 862 Crude oil, California 60° F. 915 Crude oil, Mexican 60° F. 973 Crude oil, Texas 60° F. 873 Cumene 25 860 Cyclohexane 20 779 Cyclopentane 20 745 Decane 25 726.3 Diesel fuel oil 20 to 60 15 820-950 Diethyl ether 20 714 o-Dichlorobenzene 20 1306 Dichloromethane 20 1326 Diethylene glycol 15 1120 Dichloromethane 20 1326 Dimethyl Acetamide 20 942 N,N-Dimethylformamide 20 949 Dimethyl Sulfoxide 20 1100 Dodecane 25 754.6 Ethane −89 570 Ether 25 713.5 Ethylamine 16 681 Ethyl Acetate 20 901 Ethyl Alcohol (Ethanol, pure alcohol, 20 789 grain alcohol or drinking alcohol) Ethyl Ether 20 713 Ethylene Dichloride 20 1253 Ethylene glycol 25 1097 Trichlorofluoromethane refrigerant R-11 25 1476 Dichlorodifluoromethane refrigerant R-12 25 1311 Chlorodifluoromethane refrigerant R-22 25 1194 Formaldehyde 45 812 Formic acid 10% concentration 20 1025 Formic acid 80% concentration 20 1221 Fuel oil 60° F. 890 Furan 25 1416 Furforol 25 1155 Gasoline, natural 60° F. 711 Gasoline, Vehicle 60° F. 737 Gas oils 60° F. 890 Glucose 60° F. 1350-1440 Glycerine 25 1259 Glycerol 25 1126 Heating oil 20 920 Heptane 25 679.5 Hexane 25 654.8 Hexanol 25 811 Hexene 25 671 Hydrazine 25 795 Ionene 25 932 Isobutyl Alcohol 20 802 Iso-Octane 20 692 Isopropyl Alcohol 20 785 Isopropyl Myristate 20 853 Kerosene 60° F. 820.1 Linolenic Acid 25 897 Linseed oil 25 929.1 Machine oil 20 910 Mercury 13590 Methane −164 465 Methanol 20 791 Methyl Isoamyl Ketone 20 888 Methyl Isobutyl Ketone 20 801 Methyl n-Propyl Ketone 20 808 Methyl t-Butyl Ether 20 741 N-Methylpyrrolidone 20 1030 Methyl Ethyl Ketone 20 805 Milk 15 1020-1050 Naphtha 15 665 Naphtha, wood 25 960 Napthalene 25 820 Nitric acid 0 1560 Ocimene 25 798 Octane 15 698.6 Oil of resin 20 940 Oil of turpentine 20 870 Oil, lubricating 20 900 Olive oil 20 800-920 Oxygen (liquid) −183 1140 Paraffin 800 Palmitic Acid 25 851 Pentane 20 626 Pentane 25 625 Perchlor ethylene 20 1620 Petroleum Ether 20 640 Petrol, natural 60° F. 711 Petrol, Vehicle 60° F. 737 Phenol (carbolic acid) 25 1072 Phosgene 0 1378 Phytadiene 25 823 Pinene 25 857 Propane −40 493.5 Propane, R-290 25 494 Propanol 25 804 Propylenearbonate 20 1201 Propylene 25 514.4 Propylene glycol 25 965.3 Pyridine 25 979 Pyrrole 25 966 Rape seed oil 20 920 Resorcinol 25 1269 Rosin oil 15 980 Sea water 25 1025 Silane 25 718 Silicone oil 25 965-980 Sodium Hydroxide (caustic soda) 15 1250 Sorbaldehyde 25 895 Soya bean oil 15 924-928 Stearic Acid 25 891 Sulfuric Acid 95% concentration 20 1839 Sulfurus acid −20 1490 Sugar solution 68 brix 15 1338 Sunflower oil 20 920 Styrene 25 903 Terpinene 25 847 Tetrahydrofuran 20 888 Toluene 20 867 Trichlor ethylene 20 1470 Triethylamine 20 728 Trifluoroacetic Acid 20 1489 Turpentine 25 868.2 Water, heavy 11.6 1105 Water - pure 4 1000 Water - sea 77° F. 1022 Whale oil 15 925 o-Xylene 20 880 Low density liquid or high density liquid may be sourced from, for example, waste products. For example, the low density liquid or the high density liquid may be sourced from, for example, including, but not limited to, one or more or a combination of the following: waste cooking oil, waste plastic, waste plastic converted into liquids, waste plastic converted into fuel oil, waste glycerol, waste alcohol, waste coolant, waste antifreeze, waste lubricant, waste fuel, contaminated oil, contaminated chemicals, or expired goods. Prior Art, Incorporated herein by reference: (Ocean Renewable Energy Storage (ORES) System: Analysis of an Undersea Energy Storage Concept, 2013, 10.1109/JPROC.2013.2242411, https://ieeexplore.ieee.org/document/6471167/)(https://www.renewableenergyworld.com/articles/2016/09/storing-energy-in-the-sea-a-new-design-for-marine-energy-storage.html). Application Ser. No. 14/003,567, 20140060028, Pumped-Storage Power Plant https://patents.justia.com/patent/20140060028

Third Description of Embodiments

Tidal Power System

Description:

The present embodiments may relate to systems and methods for generating energy from the change in water level due to tides. Some embodiments may be applicable to, for example, a tidal power energy generation system, which generates energy from change in water level due to, for example, tides. Some embodiments may involve using the displacement of air or other fluid from a storage region due to a rise in water level due to tides to generate energy, such as electricity. Some embodiments may involve using the movement of air or other fluid into a storage region due to a decrease in water level due to tides to generate electricity. The movement of air or displacement of air may be transferred through one or more tubes to, for example, the surface and/or may be converted to electricity using, for example, a pneumatic generator. The generation of electricity, pneumatic pump, pneumatic generator, and/or other components may be located on the surface outside the water or storage region if desired. Another gas or fluid other than air or in addition to air or in combination with air may be employed if desired. Said storage region may comprise a water or air or fluid impermeable material or structure with a concave region containing space which can be occupied by a fluid. Said concave region may be occupied by a porous material, for example, sand or rocks or cinder blocks or plastic bottles or packing material, which may contain space which can be occupied by a fluid, such as water or air. Said storage region may comprise a water or air tight liner or tarp which forms a concave region over a portion of sand or rock or cinder blocks or plastic bottles or packing material or solid material with space which can be occupied by a fluid, such as water or air. Said storage region may comprise a rigid structure such as an old ship, or a plastic container. Said storage region may comprise a bag, or bladder, or flexible structure, which may be expanded when filled with a gas or a low density liquid at, for example, lower tides, and collapsible when said gas or low density liquid is released through, for example, a generator, at higher tides. Said concave region may comprise open space which may be occupied by a fluid, such as water or air. Said concave region may be positioned such that the concave region faces the direction of the earth's surface (e.g. the direction of the force of gravity) such that a lower density fluid may be trapped in said concave region if desired. Said concave region may contain a tube with an opening inside said concave region. Said tube may be interconnected to the surface, where it may be connected to a pneumatic pump or generator or a hydraulic pump or generator. Said tube may be placed under and around said concave region, as opposed to, for example, through the material of said storage region, as this may reduce the likelihood of leaks through said storage region.

The concave region or storage region may comprise infrastructure employed for another purpose, which may include, but is not limited to, one or more or a combination of the following: a sewer system, a drainage system, a runoff water system, a wastewater system, a drainage pipe, an intake pipe, an outflow pipe, or a water storage region.

A concave region or storage region may be filled with a porous material fill. Said porous material fill may comprise, including, but not limited to, one or more or a combination of the following: sand, gravel, rock, packing material, or cinderblock, or plastic bottles, or plastic containers, or plastic buckets, or interconnected cinderblock, or interconnected plastic containers, or interconnected packing material.

The concave region or storage region may be built into or may be a component of a pre-existing or new marine structure. For example, a concave region or storage region (which may be integrated with an air tube and pneumatic generator/pump) may be fabricated as a component causeway, breakwall, building foundation, landfill or land expansion, or artificial island. Advantageously, the subsurface of waterfront land, which is rarely seen or utilized after construction, may be transformed into a means for generating renewable electricity from the tides or changes in water level of a water body.

For example, a concave region or storage region may be constructed as part of a causeway or landfill or artificial island in three general steps: 1) Air tubes may be placed in the region where the marine structure will be constructed. The air tubes may have an end which is located at a vertical height near the vertical height of the eventually constructed concave region or storage region. If advantageous, a water pipe may be placed in the region where the marine structure will be constructed to facilitate water flow in the eventually constructed concave region or storage region. Alternatively, water seepage or permeate may be the sole source of water flow if, for example, a water pipe is not employed. 2) Porous material fill, such as rock, or sand, or cinder block, or other fill materials, or other porous fill materials described herein, or a combination thereof, may be added. Said fill materials may comprise the interior of the concave region or storage region. Said fill materials may surround the air tubes. It may be desirable for said fill materials to surround, although not substantially or completely block or kink or clog an air tube. Fill materials may be carefully placed to match a design or the contour of the storage region or concave region liner. 3) A liner may be placed over said fill materials and pipe. It may be desirable for the liner to match the contour of the fill materials and it may be desirable for the liner to surround the fill materials for the full vertical depth of the fill materials or storage region. A liner may include, but is not limited to, one or more or a combination of the following: a HDPE liner, or LDPE liner, or aluminum liner, or steel liner, or metal coated liner, or metal liner, or cement liner, a cement layer, or clay liner, or landfill liner, or pond liner, or lake liner, storage basin liner, or a nylon liner, or geosynthetic liner, or PVC liner, or bag, or fabric, or textile, or mesh, or high strength polymer liner, or woven liner, or braided liner, or liner comprising multiple layers of materials for strength and fluid tightness, or tarp.

After the liner has been placed, materials comprising the rest of the marine structure may be added to, for example, construct the marine structure. If advantageous, buffer materials may be added to the top or bottom of the liner to minimize potential wear and tear or prevent the formation of perforations in the liner. Said buffer materials may include, but are not limited to, one or more or a combination of the following: sand, or burlap, or twine, or woven nyon, or Kevlar, or gravel, or clay, or mud, or foam, or cement, or concrete, or mesh, or fabric, or textile, or rubber. Advantageously, it is possible to construct the present tidal power system with no moving parts beneath the surface of the water, or underground, or inside the storage region or cavity.

For example, a concave region or storage region may be constructed as an aspect of an artificial reef or from vessels or structures which may otherwise be sunk. For example, a concave region or storage region may be constructed from using upside-down vessel or ship or boat or tank or barge. Advantageously, the hull of a ship may already be fluid tight, although additional patching or re-enforcement may be employed if desired. An example implementation may involve one or more of the following steps: 1) placing tubing and/or water pipes inside said vessel. An opening of the air tubing may be placed or attached near the bottom of the vessel (which may be near the eventual top of the storage region or concave region when said vessel becomes a storage region or concave region). Water tubing may be employed to facilitate water flow in and out of the storage region or concave region. 2) Placing porous filling material into at least a portion of said vessel. Said porous filling material may be employed to prevent the vessel from floating when the vessel open space is occupied by air. Alternatively or additionally, said vessel may be prevented from floating by using anchors and lines, which may be evenly distributed across the vessel. If necessary, a portion of the remaining air space inside the vessel may be filled with water to promote sinking. 3) Flipping said vessel upside down and placing said vessel at or near the bottom of the water body. It may be desirable for the fill material to be at least partially contained in the vessel to prevent significant uncontrolled spilling of fill material. Fill material may be contained due to at least partially covered compartments inside said vessel. Alternatively or additionally, said fill materials may be contained using a fabric or mesh or twine or net. It may be advantageous to conduct this step when the vessel is near the bottom of said water body to, for example, minimize uncontrolled spilling of fill material. Air pipes may be connected to an air pump or pneumatic generator located near, at, or above the surface. Water pipes may be open to the surrounding water body. Advantageously, if a storage region or concave region is located near the bottom of a water body, it may experience near or close to the full hydraulic head of the water body throughout the energy generation step, although this may be dependent on the vertical height of said concave region relative to the depth of the water body and water level difference between low and high tide.

Some embodiments may generate electricity from the difference in hydraulic pressure in a storage region in a water body due to the change with water level, which may be due to tides. An embodiment may involve a storage region beneath the surface of a water body. During relatively lower water levels or tides, air may be pumped into the storage region using, for example, one or more tubes, displacing water in said storage region. During relatively higher water levels or tides, water may be allowed to displace air from said storage region, and said air may pass through, for example, one or more tubes into pneumatic generator, generating useful work or electricity. It is important to note that at higher water levels or tides, the hydraulic pressure in the storage region may be significantly greater than the hydraulic pressure in the storage region during lower water levels or tides. Net energy or electricity may be generated due to, for example, the significantly greater amount of energy or electricity generated from air being displaced into a generator at higher tides or water levels than the energy or electricity required to pump air into said storage region during lower water levels or tides. Net energy or electricity generated may comprise the difference in between the energy generated during higher water levels or tides compared to the energy consumed during lower water levels or tides.

Embodiments may generate electricity during one or more of the tide cycles. For example, some embodiments may generate electricity during four tide cycles in a ˜1 day period (for example: 2 high tides, two low tides)—an example of this may be an embodiment employing an underground cavity with depth in the range of the ocean water level at higher or lower or both tides. For example, some embodiments may generate electricity during two tide cycles in a ˜1 day period (for example: 2 high tides)—an example of this may be an embodiment employing an under water storage region at below or near or about same water depth of the low tide depth in a region. For example, some embodiments may generate electricity during less cycles than their available capacity—an example of this may be an embodiment employing an underground cavity with depth in the range of the ocean water level at higher or lower or both tides wherein the process generates electricity during only higher tides. An embodiment which only generates electricity during higher tides may be advantageous as some cavities may not be structurally suitable for partial vacuums, which may be required to generate electricity during all four tide movements during a day.

The process may employ a hydroelectric or hydro generator if advantageous. It is important to note to minimize costs and maximize longevity, it may be advantageous to employ a pneumatic generator powered by air displacement.

Cavity, storage region, or concave region may be analogous or synonym terms.

Example Advantages:

-   -   Cost:         -   Material cost is low. Material cost may simply comprise a             liner, pipes, filling material (if not already available in             the surrounding environment), and pneumatic generator or             pump         -   Labor cost may vary depending on whether the installation is             part of another project, such as the construction of a             marine structure, and whether the installation required             digging beneath the surface of the ground or dredging.     -   Resilience and Durability:         -   Some embodiments may be located underground or beneath the             surface of a water body, reducing potential hazards from             waves and debris         -   Some embodiments may have no moving parts beneath the             surface of the water body, reducing or eliminating potential             complications from corrosion, fouling, or debris         -   Moving parts may, if desired, not be in contact or direct             contact with water or the water body, reducing their cost             and increasing their expected lifespan     -   Efficiency         -   Pneumatic generators powered using relatively low pressure             pressurized air can produce electricity at an efficiency             greater than 50%, or greater than 60%, or greater than 70%,             or greater than 80%, or greater than 90%.             Example Step by Step Descriptions             Underground Air & Water Cavity:

Overview:

FIGS. 14-19 may show embodiments employing an underground storage region or cavity. Each figure may show an example step in the process of generating electricity from changes in water level due to, for example, including, but not limited to, tides. In FIGS. 14-19, the storage region or cavity may comprise mostly open space for fluid, such as air or water, to occupy.

FIG. 14: Step 1 (Higher Tide, Filling, Electricity Generation): FIG. 14 may show an embodiment where electricity is being generated. Air is allowed to be released through the opening of a valve in the air tube or pneumatic pump, which allows air to exit storage region through a pipe into a pneumatic generator, which may generate electricity. Due to the relatively high water level in the surrounding or nearby water body relative to the water level in the storage region, the air pressure in the storage region may be greater than the atmosphere air pressure. Water from the surrounding or nearby water body may pass through a pump or travel via seepage into the storage region, displacing the air in said storage region. The flow rate of air exiting the storage region and the rate of water entering the storage region may be controlled by controlling the flow rate of air entering the pneumatic generator.

FIG. 15: Step 2 (High Tide, Cavity Full): FIG. 15 may show an embodiment where the storage region is nearly full with water. The storage region may be considered nearly full with water when it achieves either of the following: 1) the water level in the storage region is near or at the maximum water level in the nearby water body's recent tide range; or 2) the water volume reaches the maximum practical volumetric capacity of the storage region.

FIG. 16: Step 3 (Lower Tide, Emptying, Generating Electricity): FIG. 16 may show an embodiment generating electricity when the surrounding water body water level is relatively low compared to the water level inside the storage region. Energy may be generated due to the flow of air into the storage region as water exits said storage region, and where said flow of air powers, for example, a pneumatic generator. The flow of water out of said storage region may be through a water pipe or water seepage. It is important to note depth of the storage region or, if a water pipe is connected to the storage region, the depth of the water pipe, may desirably be lower than the depth of the water in water body to prevent uncontrolled water exiting or air entering the storage region. Air flow and water exiting may be controlled through the opening of a valve in connected to the air tube or pneumatic generator.

FIG. 17: Step 4 (Lower Tide, Empty): FIG. 17 may show an embodiment where the storage region is nearly empty with water. The storage region may be considered nearly empty with water when it achieves one of the following: 1) the water level in the storage region is near or at the minimum water level in the nearby water body's recent tide range; or 2) there is no water in the storage region.

FIG. 18: Step 4 Alternative (Lower Tide, Empty, depending on time of year and location): FIG. 18 may show an embodiment where the storage region is fully empty with water. It is important to note that energy generation from water exiting a storage region may require the water pipe or the storage region to be at least partially beneath the surface of the water to prevent unintentional air or water flow. It is important to note that a storage region occupied almost entirely by air may maximize the potential energy generation capacity.

FIG. 19: Step 5 (Lower Tide, Pump remaining water out): FIG. 19 may show an embodiment where air is pumped into a storage region to remove residual water. Pumping air into the storage region may be conducted, for example, while the water level in the surrounding water body is relatively low. The energy required to pump air into the storage region (and displacing residual water) at a lower tide may be significantly less the than the energy generated from the increase in displaceable volume occupied by air in the storage region. Additionally, air may be pumped into the storage region to remove water which may have been trapped in the air pipe.

Example Embodiment where Water/Air Cavity or Storage Region Contains a Porous Material:

Overview:

FIGS. 20-23 may show embodiments employing an underground storage region or cavity. Each figure may show an example step in the process of generating electricity from changes in water level due to, for example, including, but not limited to, tides. In FIGS. 14-19, the storage region or cavity may comprise mostly porous filling material, which may contain space for fluid, such as air or water, to occupy. The steps for generating electricity may be similar to the steps shown in FIGS. 14-19.

FIG. 20: Step 1 (Higher Tide, Filling, Electricity Generation): FIG. 20 shows an example embodiment where water/air cavity or storage region contains a porous material.

FIG. 21: Step 2 (High Tide, Cavity Full): FIG. 21 shows an example embodiment where water/air cavity or storage region contains a porous material.

FIG. 22: Step 3 (Lower Tide, Emptying, Generating Electricity): FIG. 22 shows an example embodiment where water/air cavity or storage region contains a porous material.

FIG. 23: Step 4 (Lower Tide, Empty): FIG. 23 shows an example embodiment where water air cavity or storage region contains a porous material.

Under Water Vessel (May be Near Full Head Height Throughout Power Generation):

FIG. 24: Step 1 (Higher Tide, Filling, Generating Electricity): FIG. 24 shows an example embodiment where water/air cavity or storage region is located on or within a water body.

FIG. 25: Step 2 (Higher Tide, Full): FIG. 25 shows an example embodiment where water/air cavity or storage region is located on or within a water body.

FIG. 26: Step 3 (Lower Tide, Emptying): FIG. 26 shows an example embodiment where water/air cavity or storage region is located on or within a water body.

FIG. 27: Alternative Step 3 (Lower Tide, Emptying, Depending on Tide and Location): FIG. 27 shows an example embodiment where water/air cavity or storage region is located on or within a water body.

FIG. 28: Step 4 (Lower Tide, Empty): FIG. 28 shows an example embodiment where water/air cavity or storage region is located on or within a water body.

FIG. 29: FIG. 29 shows an example embodiment with a floating pump or generator station.

It will be appreciated that while many of the above figures show the vessel or other storage structure at or near the bottom of the water body, it may be located at any convenient location below the surface. In some embodiments it may be moored to the bottom and/or the top of the water body.

Air may be substituted with other fluids described herein. In the case where the fluid comprises a liquid, a hydraulic or hydroelectric generator may be employed instead of a pneumatic generator.

Relatively higher tides are when the water level in a water body is higher than the water level during relatively lower tides. Water level changes may be due to primarily changes in the water level due to gravitational tides.

EXAMPLE EXEMPLARY EMBODIMENTS

-   -   A tidal power system comprising:         -   A region comprising a cavity, or concave region, or a             storage region surrounded by at least a portion water             impermeable material         -   Wherein water displaces air from said region at relatively             high tides,         -   Wherein air displaces water at relatively lower tides         -   Wherein electricity is generated from movement of air to or             from said region

EXAMPLE EXEMPLARY SUB-EMBODIMENTS

-   -   Wherein energy or electricity is generated using a pneumatic         turbine or generator     -   Wherein said region is located beneath the surface of the         ground, or inside a causeway, or a landfill, or an artificial         island, or a breakwall, or a building foundation, or a structure         foundation, or a combination thereof     -   Wherein said storage region contains a porous fill material     -   Wherein said porous fill material comprises one or more or a         combination of the following: sand, gravel, rock, packing         material, or cinderblock, or plastic bottles, or plastic         containers, or plastic buckets, or interconnected cinderblock,         or interconnected plastic containers, or interconnected packing         material     -   Wherein said water impermeable material may comprise a liner     -   Wherein air exits and enters said region using a pipe     -   Wherein said pipe has an opening inside said storage region or         an opening above the surface of the water or both     -   Wherein water enters or exits said region via water seepage     -   Wherein water enters or exits said region via a pipe     -   Wherein water enters or exits said region through an opening in         said region or water impermeable material     -   Wherein said is structurally rigid     -   Wherein said region is structurally flexible or expandable or         collapsible and may comprise a bladder, bag, or similar device     -   Wherein said air is located inside said structurally flexible         region and said structurally flexible region is inflated during         lower tides and collapsed during higher tides     -   Wherein said collapsing generates electricity through the         displacement of air from said structurally flexible region into         a pneumatic generator     -   Wherein said region comprises infrastructure employed for         another purpose, such as one or more or a combination of the         following: a sewer system, a drainage system, a runoff water         system, a wastewater system, a drainage pipe, an intake pipe, an         intake system, an outflow pipe, an outflow system, or a storage         region.     -   Wherein a liner comprises one or more or a combination of the         following: a HDPE liner, or LDPE liner, or aluminum liner, or         steel liner, or metal coated liner, or metal liner, or cement         liner, a cement layer, or clay liner, or landfill liner, or pond         liner, or lake liner, storage basin liner, or a nylon liner, or         geosynthetic liner, or PVC liner, or bag, or fabric, or textile,         or mesh, or high strength polymer liner, or woven liner, or         braided liner, or liner comprising multiple layers of materials         for strength and fluid tightness, or tarp.     -   Wherein said region is constructed as an aspect of an artificial         reef or from vessels or structures which may otherwise be sunk         or a combination thereof     -   Wherein air is pumped into said region during lower tides and         air is released from said region into a generator during higher         tides     -   Wherein the energy generated during higher tides exceeds the         energy consumed during lower tides     -   Wherein air is pumped into said region to store electricity     -   Wherein air is released from said region to generate electricity     -   Wherein the present invention can function as a tidal power         energy generation device, an energy storage device, or both

SPECIFIC EMBODIMENTS

Embodiments for “Systems and Methods for Preventing Fouling of Marine Structures”

1. A system for reducing fouling on an aquatic structure comprising:

an aquatic structure comprising at least one surface exposed to water;

a concave region on at least one portion of the surface exposed to water wherein said concave region is configured to maintain a substantially non-contiguous physical separation between water and said region and wherein at least a portion of said concave region is occupied with a gas. 2. The system of Embodiment 1 wherein the substantially non-contiguous physical separation is maintained by controlling the amount of gas in said concave region. 3. The system of Embodiment 1 further comprising a controller and a gas source operably connected to said concave region wherein the controller and gas source control the amount of gas. 4. The system of Embodiment 3 wherein said controller and gas source are employed to displace water with gas in at least a portion of said concave region. 5. The system of Embodiment 1 wherein the said gas pocket is controllably immobilized for a controlled period of time. 6. The system of Embodiment 5 wherein said time is at least about 5 seconds. 7. The system of Embodiment 1 wherein said substantially non-contiguous physical separation is present greater than 30% of the time said structure is in use. 8. A system for reducing fouling on an aquatic structure comprising: an aquatic structure comprising at least one surface exposed to water when the structure is in use; a concave region on at least one portion of the surface exposed to water wherein said concave region is configured to maintain a substantially non-contiguous physical separation between water and said region. 9. The system of Embodiment 8 wherein the volume beneath said concave region is adjustable. 10. The system of Embodiment 8 wherein the surface area of the concave region is adjustable. 11. The system of Embodiment 8 wherein the height of the concave region relative to water is adjustable. 12. The system of Embodiment 8 wherein at least one of the volume beneath said concave region, the surface area of the concave region, or the height of the concave region above water, is adjusted by changing the surface morphology of or on the concave region. 13. The system of Embodiment 8 wherein at least a portion of the surface exposed to water is substantially hydrophobic. 14. An improved aquatic structure comprising: a structure comprising at least one surface exposed to water when the structure is in use wherein the improvement comprises: configuring at least a portion of said surface exposed to water such that said portion has a non-contiguous separation with water when the structure is in use and wherein the portion having a non-contiguous separation with water provides a gas pocket between said portion and water when the structure is in use. 15. The improved aquatic structure of Embodiment 14 wherein the amount of substantially non-contiguous physical separation with water of the surface exposed to water is controlled by adjusting the amount of gas in the pocket. 16. The improved aquatic structure of Embodiment 14 wherein said non-contiguous separation is present greater than 30% of the time said structure is in use. 17. The improved aquatic structure of Embodiment 14 wherein said portion configured to be non-contiguous reduces visible fouling by at least 50% as compared to a similar structure lacking said non-contiguous portion. 18. The improved aquatic structure of Embodiment 14 wherein the amount of gas in the pocket is adjustable. 19. The improved aquatic structure of Embodiment 14 wherein the volume of the gas pocket is adjustable. 20. The improved aquatic structure of Embodiment 14 wherein the surface area or volume of the non-contiguous separated portion is adjustable. 21. The system of Embodiment 14 wherein the height of the non-contiguous separated portion with respect to water is adjustable. Embodiments for “Low Density Fluid Displacement to Generate Power” 1. A system for generating electricity comprising: a first storage reservoir near the surface of a body of water and configured to store a low density fluid which is substantially immiscible with water; a second storage reservoir located below the surface of a body of water and configured to store water; a pump; and a generator; wherein the pump, generator, and the first and second reservoir are operatively connected such that electricity is stored by displacing water in the second storage reservoir by pumping low density fluid in the first storage reservoir to the second storage reservoir and electricity is generated (or discharge) by allowing the low density fluid in the second storage reservoir to return to the first reservoir. 2. The system of Embodiment 1 wherein the pump and the generator may be the same unit. 3. The system of Embodiment 1 wherein said second storage reservoir comprises an expandable or contractible structure. 4. The system of Embodiment 1 wherein said second storage reservoir comprises a bladder, a bag, or a balloon. 5. The system of Embodiment 1 wherein said second storage reservoir contains a concave region with an opening near the bottom of said concave region open to the body of water. 6. The system of Embodiment 1 wherein said second storage reservoir is tethered to the bottom of said water body. 7. The system of Embodiment 1 wherein the low density fluid comprises a hydrocarbon liquid or natural gas. 8. The system of Embodiment 1 wherein the low density fluid comprises compressed natural gas or liquid natural gas. 9. The system of Embodiment 1 which is operatively connected to a unit requiring electricity. 10. A process to generate energy comprising: storing energy by displacing at least a portion of a first fluid having a first density with a second fluid having a second density which is lower than said first fluid wherein said first and second fluid are substantially immiscible in each other; allowing a power discharge by displacing at least a portion of the lower density second fluid with the first higher density fluid; wherein said generating step, allowing step, or both are facilitated by pressure and gravity. 11. The process of Embodiment 10 wherein said generating step, allowing step, or both occur beneath a surface of water wherein said water is employed to facilitate pressure. 12. The process of Embodiment 10 wherein said first fluid is water. 13. The process of Embodiment 10 wherein said second fluid comprises compressed natural gas, liquid natural gas, liquid hydrocarbon, petroleum ether, or crude oil. 14. The process of Embodiment 10 wherein the second fluid having a second density is stored near the surface of a body of water. 15. The process of Embodiment 10 which further comprises converting the power discharge to electricity. 16. The process of Embodiment 10 which further comprises storing said power discharge. 17. The process of Embodiment 10 which further comprises converting the power discharge to electricity. 18. The process of Embodiment 10 wherein the first or second fluid comprise a waste fluid. 19. The process of Embodiment 10 wherein the first or second fluid comprise a fluid generated from a solid waste. 20. The process of Embodiment 10 wherein the first or second fluid comprise a cooking oil. Embodiments for “Underwater Energy Storage and Electricity” 1. A process for generating electricity from tides comprising:

providing a cavity which is operatively linked to tidal waters and configured such that air is displaced with water at higher tides and such that water is displaced with air at lower tides;

displacing at least a portion of air within the cavity with water at higher tides;

displacing at least a portion of water within the cavity with air at lower tides;

wherein the displacing of water, air or both generates power.

2. The process of Embodiment 1 wherein the cavity is open on bottom.

3. The process of Embodiment 1 further comprising transferring at least a portion of displaced air to a pneumatic generator.

4. The process of Embodiment 1 which further comprises controlling the flow rate of air during displacing of air.

5. The process of Embodiment 1 which further comprises controlling the flow rate of water during displacing of air.

6. The process of Embodiment 1 wherein the cavity is above ground.

7. The process of Embodiment 1 wherein the cavity is below ground.

8. The process of Embodiment 1 wherein the cavity is at least partially submerged in a tidal water body.

9. The process of Embodiment 1 further comprising transferring at least a portion of displaced air to a pneumatic generator through one or more pipes.

10. The process of Embodiment 1 wherein the cavity comprises a flexible liner.

11. The process of Embodiment 1 wherein the cavity is rigid.

12. The process of Embodiment 1 wherein the cavity is expandable or collapsible.

13. The process of Embodiment 1 which is configured such that power generated at higher tides exceeds any power consumed during lower tides.

14. A process for generating electricity from tides comprising:

providing a cavity which is at least partially filled with a porous material and air which cavity is operatively linked to tidal waters and configured such that air is displaced with water at higher tides and such that water is displaced with air at lower tides;

displacing at least a portion of air within the cavity with water at higher tides;

displacing at least a portion of water within the cavity with air at lower tides;

wherein the displacing of water, air or both generates power.

15. The process of Embodiment 14 wherein the porous material comprises sand, gravel, rock, packing material, or cinderblock, or plastic bottles, or plastic containers, or plastic buckets, or interconnected cinderblock, or interconnected plastic containers, interconnected packing material, or mixtures thereof. 16. The process of Embodiment 14 wherein the cavity comprises a flexible liner. 17. The process of Embodiment 14 wherein the cavity is rigid. 18. The process of Embodiment 14 wherein the cavity is expandable or collapsible. 19. The process of Embodiment 14 further comprising transferring at least a portion of displaced air to a pneumatic generator. 20. The process of Embodiment 14 which further comprises controlling the flow rate of water during displacing of air. Further Discussion of Second Description of Embodiments

Additional Energy Storage Embodiments Summary

The present invention pertains to a system for storing energy. The present invention stores energy in the hydrostatic pressure difference between a lesser density liquid and a greater density liquid over the same hydraulic head or depth.

The present invention may involve storing energy by displacing water or other greater density liquid with a lesser density liquid. Said displacing of water with a lesser density liquid may involve pumping lesser density liquid to a greater depth beneath the surface of water or other body of liquid. Said pumping may consume power, such as electricity, and convert said power into gravitational potential energy and/or energy stored in a hydrostatic pressure difference. Said stored energy may be converted back into power by allowing said lesser density liquid to be released from said greater depth beneath the surface of water or other body of liquid to a lesser depth beneath the surface of water or other body of liquid, passing through a generator in the process.

DESCRIPTION OF FIGURES

FIG. 30: FIG. 30 may show an energy storage system where the first storage reservoir is located on land and the pump and/or generator is located on land. The second storage reservoir is located beneath the surface of a water body at a greater hydrostatic pressure and/or greater depth beneath the surface of a water body than the first storage reservoir. The first storage reservoir, the pump and/or generator, and the second storage reservoir may be connected using pipes. FIG. 30 may show the energy storage system undergoing charging. Charging may involve storing power by pumping low density liquid from the first storage reservoir to the second storage reservoir. Storage reservoirs may comprise expandable and/or contractable or collapsible tanks. For example, during charging, the first storage reservoir may contract or collapse into a smaller volume as liquid is pumped from the first storage reservoir to the second storage reservoir. For example, during charging, the second storage reservoir may expand into a larger volume as liquid is pumped from the first storage reservoir to the second storage reservoir.

FIG. 31: FIG. 31 may show an energy storage system where the first storage reservoir is located on land and the pump and/or generator is located on land. The second storage reservoir is located beneath the surface of a water body at a greater hydrostatic pressure and/or greater depth beneath the surface of a water body than the first storage reservoir. The first storage reservoir, the pump and/or generator, and the second storage reservoir may be connected using pipes. FIG. 31 may show the energy storage system undergoing discharging. Discharging may involve releasing stored energy by allowing the release of lower density liquid from the first storage reservoir to the second storage reservoir, generating power in the process by allowing said low density liquid to pass through a generator. Storage reservoirs may comprise expandable and/or contractable or collapsible tanks. For example, during discharging, the first storage reservoir may expand into a larger volume as liquid is released from the second storage reservoir to the first storage reservoir. For example, during discharging, the second storage reservoir may contract or collapse into a smaller volume as liquid is released from the second storage reservoir to the first storage reservoir.

FIG. 32: FIG. 32 may show an energy storage system where the first storage reservoir is located near, at, or beneath the surface of a water body and/or the pump and/or generator is located near, at or beneath the surface of a water body. The second storage reservoir is located beneath the surface of a water body at a greater hydrostatic pressure and/or greater depth beneath the surface of a water body than the first storage reservoir. The first storage reservoir, the pump and/or generator, and the second storage reservoir may be connected using pipes. FIG. 32 may show the energy storage system undergoing charging.

FIG. 33: FIG. 33 may show an energy storage system where the first storage reservoir is located near, at, or beneath the surface of a water body and/or the pump and/or generator is located near, at or beneath the surface of a water body. The second storage reservoir is located beneath the surface of a water body at a greater hydrostatic pressure and/or greater depth beneath the surface of a water body than the first storage reservoir. The first storage reservoir, the pump and/or generator, and the second storage reservoir may be connected using pipes. FIG. 33 may show the energy storage system undergoing discharging.

Example Figure Keys

FIG. 30 Diagram Element Description 1 ‘1’ or the first storage reservoir, may comprise a tank or reservoir storing a relatively low density liquid at a lesser hydrostatic pressure than the second storage region, ‘2’. ‘1’ may exist at a pressure at or near the ambient pressure surrounding ‘1’. Alternatively, or additionally, ‘1’ may exist at a pressure greater than ambient pressure surrounding ‘1’, however less than the hydrostatic pressure of the second storage reservoir (‘2’). Alternatively, or additionally, ‘1’ may exist at a pressure less than ambient pressure surrounding ‘1’, which may be less than the hydrostatic pressure of the second storage reservoir (‘2’). In FIG. 30, the process may be undergoing ‘charging’. During charging, low density liquid may be pumped from ‘1’ using a pump (‘3’) to ‘2’. ‘2’ may be located beneath the surface of a body of liquid with greater density than the low density liquid and/or may exist at a greater hydrostatic pressure than ‘1’. If ‘1’ comprises a contractable or collapsible tank, the total volume occupied by the tank or total volume of liquid in the tank may decrease during ‘charging’. 2 ‘2’ or the second storage reservoir may comprise a tank or reservoir storing a relatively low density liquid at a greater hydrostatic pressure than the first storage region, ‘1’. ‘2’ may exist at a pressure at or near the ambient pressure surrounding ‘2’. Alternatively, or additionally, ‘2’ may exist at a pressure greater than ambient pressure surrounding ‘2’ and/or greater than the hydrostatic pressure of the ‘1’. Alternatively, or additionally, ‘2’ may exist at a pressure less than ambient pressure surrounding ‘2’, which may be greater than the hydrostatic pressure of ‘1’. In FIG. 30, the process may be undergoing ‘charging’. During charging, low density liquid may be pumped from ‘1’ using a pump (‘3’) to ‘2’. ‘2’ may be located beneath the surface of a body of liquid with greater density than the low density liquid and/or may exist at a greater hydrostatic pressure than ‘1’. If ‘2’ comprises a contractable or collapsible tank, the total volume occupied by the tank or total volume of liquid in the tank may increase during ‘charging’. 3 ‘3’ may comprise a pump and/or generator. ‘3’ may be employed to pump low density liquid from ‘1’ to ‘2’. ‘3’ may comprise a pump, which may be reversibly employed as a generator. ‘3’ may comprise a pump separate from a generator. ‘3 may comprise multiple pumps and generators or reversible pump/generators. ‘3’ may act as a valve which separates relatively high pressure low density liquid in the pipe ‘Line/Arrow Between ‘2’ and ‘3’’ from the relatively low pressure low density liquid in the pipe ‘Line/Arrow Between ‘1’ and ‘3’’. In FIG. 30, ‘3’ may be pumping low density liquid from ‘1’ to ‘2’, which may comprise charging the energy storage device. Electricity ‘Electricity’ may comprise a source of electricity or an application requiring electricity or both. ‘Electricity’ may encompass transmission equipment and/or electricity grid infrastructure and/ or applications generating or using electricity. In FIG. 30, ‘Electricity’ may involve supplying electricity to ‘3’ to power the pumping of low density liquid from reservoir ‘1’ to reservoir ‘2’. Line/Arrow Between The present diagram element may comprise a means for ‘1’ and ‘3’ transferring low density liquid from ‘1’ to ‘3’. For example, the present diagram element may comprise a pipe or set of pipes. Said pipe may be compatible with the low density liquid. Line/Arrow Between The present diagram element may comprise a means for ‘3’ and ‘2’ transferring low density liquid from ‘3’ to ‘2’. For example, the present diagram element may comprise a pipe or pipes. The present diagram element may involve a pipe which experiences a pressure difference between internal liquid contents and liquid surrounding the pipe. Said pressure difference may vary depending on the depth of the section of pipe beneath the surface of the water body, the depth of reservoir ‘2’ compared to reservoir ‘1’ or to ‘3’, the hydrostatic pressure difference between reservoir ‘1’ and reservoir ‘2’, and/or the density of the low density liquid and/or the density of the liquid surrounding the section of pipe. In FIG. 30, the present diagram element may involve transferring low density liquid from ‘3’ to reservoir ‘2’. Land ‘Land’ may comprise a solid structure or surface or earth which ‘1’ and/or ‘3’ are situated in FIG. 30. The weight of ‘1’ and/or ‘3’ may be supported by said land in FIG. 30. Water ‘Water’ may comprise the body of liquid in which reservoir ‘2’ is submerged.

FIG. 31 Diagram Element Description 1 ‘1’ or the first storage reservoir, may comprise a tank or reservoir storing a relatively low density liquid at a lesser hydrostatic pressure than the second storage region, ‘2’. ‘1’ may exist at a pressure at or near the ambient pressure surrounding ‘1’. Alternatively, or additionally, ‘1’ may exist at a pressure greater than ambient pressure surrounding ‘1’, however less than the hydrostatic pressure of the second storage reservoir (‘2’). Alternatively, or additionally, ‘1’ may exist at a pressure less than ambient pressure surrounding ‘1’, which may be less than the hydrostatic pressure of the second storage reservoir (‘2’). In FIG. 31, the process may be undergoing ‘discharging’. During discharging, low density liquid may be released from ‘2’ to ‘1’, generating electricity by powering generator ‘3’. ‘2’ may be located beneath the surface of a body of liquid with greater density than the low density liquid and/or may exist at a greater hydrostatic pressure than ‘1’. If ‘1’ comprises a contractable or collapsible tank, the total volume occupied by the tank or total volume of liquid in the tank may increase during ‘discharging’. 2 ‘2’ or the second storage reservoir may comprise a tank or reservoir storing a relatively low density liquid at a greater hydrostatic pressure than the first storage region, ‘1’. ‘2’ may exist at a pressure at or near the ambient pressure surrounding ‘2’. Alternatively, or additionally, ‘2’ may exist at a pressure greater than ambient pressure surrounding ‘2’ and/or greater than the hydrostatic pressure of the ‘1’. Alternatively, or additionally, ‘2’ may exist at a pressure less than ambient pressure surrounding ‘2’, which may be greater than the hydrostatic pressure of ‘1’. In FIG. 31, the process may be undergoing ‘discharging’. During discharging, low density liquid may be released from ‘2’ to ‘1’, generating electricity by powering generator ‘3’. ‘2’ may be located beneath the surface of a body of liquid with greater density than the low density liquid and/or may exist at a greater hydrostatic pressure than ‘1’. If ‘2’ comprises a contractable or collapsible tank, the total volume occupied by the tank or total volume of liquid in the tank may decrease during ‘discharging’. 3 ‘3’ may comprise a pump and/or generator and/or valve. ‘3’ may be employed to generate power from low density liquid transferred from ‘2’ to ‘1’ during discharging. ‘3’ may be employed to pump low density liquid from ‘1’ to ‘2’ during charging. ‘3’ may comprise a pump, which may be reversibly employed as a generator. ‘3’ may comprise a pump separate from a generator. ‘3’ may comprise multiple pumps and generators or reversible pump/generators. ‘3’ may act as a valve which separates relatively high pressure low density liquid in the pipe ‘Line/Arrow Between ‘2’ and ‘3’’ from the relatively low pressure low density liquid in the pipe ‘Line/Arrow Between ‘1’ and ‘3’’. In FIG. 31, ‘3’ may be generating power from the release of low density liquid from ‘2’ to ‘1’, which may comprise discharging the energy storage device. Electricity ‘Electricity’ may comprise a source of electricity or an application requiring electricity or both. ‘Electricity’ may encompass transmission equipment and/or electricity grid infrastructure and/ or applications generating or using electricity. In FIG. 31, ‘Electricity’ may comprise electricity generated by ‘3’ during discharging and/or the transmission and/or utilization of said electricity. Line/Arrow Between The present diagram element may comprise a means for ‘1’ and ‘3’ transferring low density liquid from ‘3’ to ‘1’. For example, the present diagram element may comprise a pipe or set of pipes. Said pipe may be compatible with the low density liquid. Line/Arrow Between The present diagram element may comprise a means for ‘3’ and ‘2’ transferring low density liquid from ‘2’ to ‘3’. For example, the present diagram element may comprise a pipe or pipes. The present diagram element may involve a pipe which experiences a pressure difference between internal liquid contents and liquid surrounding the pipe. Said pressure difference may vary depending on the depth of the section of pipe beneath the surface of the water body, the depth of reservoir ‘2’ compared to reservoir ‘1’ or to ‘3’, the hydrostatic pressure difference between reservoir ‘1’ and reservoir ‘2’, and/or the density of the low density liquid and/or the density of the liquid surrounding the section of pipe. In FIG. 31, the present diagram element may involve transferring low density liquid from ‘2’ to ‘3’. Land ‘Land’ may comprise a solid structure or surface or earth which ‘1’ and/or ‘3’ are situated in FIG. 31. The weight of ‘1’ and/or ‘3’ may be supported by said land in FIG. 31. Water ‘Water’ may comprise the body of liquid in which reservoir ‘2’ is submerged.

FIG. 32 Diagram Element Description 1 ‘1’ or the first storage reservoir, may comprise a tank or reservoir storing a relatively low density liquid at a lesser hydrostatic pressure than the second storage region, ‘2’. ‘1’ may exist at a pressure at or near the ambient pressure surrounding ‘1’. Alternatively, or additionally, ‘1’ may exist at a pressure greater than ambient pressure surrounding ‘1’, however less than the hydrostatic pressure of the second storage reservoir (‘2’). Alternatively, or additionally, ‘1’ may exist at a pressure less than ambient pressure surrounding ‘1’, which may be less than the hydrostatic pressure of the second storage reservoir (‘2’). In FIG. 32, the process may be undergoing ‘charging’. During charging, low density liquid may be pumped from ‘1’ to ‘2’, using pump ‘3’. ‘2’ may be located beneath the surface of a body of liquid with greater density than the low density liquid and/or may exist at a greater hydrostatic pressure than ‘1’. If ‘1’ comprises a contractable or collapsible tank, the total volume occupied by the tank or total volume of liquid in the tank may decrease during ‘charging’. 2 ‘2’ or the second storage reservoir may comprise a tank or reservoir storing a relatively low density liquid at a greater hydrostatic pressure than the first storage region, ‘1’. ‘2’ may exist at a pressure at or near the ambient pressure surrounding ‘2’. Alternatively, or additionally, ‘2’ may exist at a pressure greater than ambient pressure surrounding ‘2’ and/or greater than the hydrostatic pressure of the ‘1’. Alternatively, or additionally, ‘2’ may exist at a pressure less than ambient pressure surrounding ‘2’, which may be greater than the hydrostatic pressure of ' 1’. In FIG. 32, the process may be undergoing ‘charging’. During charging, low density liquid may be pumped from ‘1’ to ‘2’, using pump ‘3’. ‘2’ may be located beneath the surface of a body of liquid with greater density than the low density liquid and/or may exist at a greater hydrostatic pressure than ‘1’. If ‘2’ comprises a contractable or collapsible tank, the total volume occupied by the tank or total volume of liquid in the tank may increase during ‘charging’. 3 ‘3’ may comprise a pump and/or generator and/or valve. ‘3’ may be employed to generate power from low density liquid transferred from ‘2’ to ‘1’ during discharging. ‘3’ may be employed to pump low density liquid from ‘1’ to ‘2’ during charging. ‘3’ may comprise a pump, which may be reversibly employed as a generator. ‘3’ may comprise a pump separate from a generator. ‘3’ may comprise multiple pumps and generators or reversible pump/generators. ‘3’ may act as a valve which separates relatively high pressure low density liquid in the pipe ‘Line/Arrow Between ‘2’ and ‘3’’ from the relatively low pressure low density liquid in the pipe ‘Line/Arrow Between ‘1’ and ‘3’’. In FIG. 32, ‘3’ may be pumping low density liquid from ‘1’ to ‘2’, which may comprise charging the energy storage device. Electricity ‘Electricity’ may comprise a source of electricity or an application requiring electricity or both. ‘Electricity’ may encompass transmission equipment and/or electricity grid infrastructure and/ or applications generating or using electricity. In FIG. 32, ‘Electricity’ may comprise electricity consumed by ‘3’ (and stored by the energy storage device) during charging. In FIG. 32, electricity may be transferred using undersea cables or using underground cables or using subsea cables or using light, or using microwaves, or by oxidation of a fuel, or by reversible consumption of a fuel, or by discharging a transportable battery. Line/Arrow Between The present diagram element may comprise a means for ‘1’ and ‘3’ transferring low density liquid from ‘1’ to ‘3’. For example, the present diagram element may comprise a pipe or set of pipes. Said pipe may be compatible with the low density liquid. Line/Arrow Between The present diagram element may comprise a means for ‘3’ and ‘2’ transferring low density liquid from ‘3’ to ‘2’. For example, the present diagram element may comprise a pipe or pipes. The present diagram element may involve a pipe which experiences a pressure difference between internal liquid contents and liquid surrounding the pipe. Said pressure difference may vary depending on the depth of the section of pipe beneath the surface of the water body, the depth of reservoir ‘2’ compared to reservoir ‘1’ or to ‘3’, the hydrostatic pressure difference between reservoir ‘1’ and reservoir ‘2’, and/or the density of the low density liquid and/or the density of the liquid surrounding the section of pipe. In FIG. 32, the present diagram element may involve transferring low density liquid from ‘3’ to ‘2’. Water ‘Water’ may comprise the body of liquid which ‘1’, ‘2’, and/or ‘3’ are situated and/or submerged in FIG. 32.

FIG. 33 Diagram Element Description 1 ‘1’ or the first storage reservoir, may comprise a tank or reservoir storing a relatively low density liquid at a lesser hydrostatic pressure than the second storage region, ‘2’. ‘1’ may exist at a pressure at or near the ambient pressure surrounding ‘1’. Alternatively, or additionally, ‘1’ may exist at a pressure greater than ambient pressure surrounding ‘1’, however less than the hydrostatic pressure of the second storage reservoir (‘2’). Alternatively, or additionally, ‘1’ may exist at a pressure less than ambient pressure surrounding ‘1’, which may be less than the hydrostatic pressure of the second storage reservoir (‘2’). In FIG. 33, the process may be undergoing ‘discharging’. During discharging, low density liquid may be released from ‘2’ to ‘1’, generating electricity by powering generator ‘3’. ‘2’ may be located beneath the surface of a body of liquid with greater density than the low density liquid and/or may exist at a greater hydrostatic pressure than ‘1’. If ‘1’ comprises a contractable or collapsible tank, the total volume occupied by the tank or total volume of liquid in the tank may increase during ‘discharging’. 2 ‘2’ or the second storage reservoir may comprise a tank or reservoir storing a relatively low density liquid at a greater hydrostatic pressure than the first storage region, ‘1’. ‘2’ may exist at a pressure at or near the ambient pressure surrounding ‘2’. Alternatively, or additionally, ‘2’ may exist at a pressure greater than ambient pressure surrounding ‘2’ and/or greater than the hydrostatic pressure of the ‘1’. Alternatively, or additionally, ‘2’ may exist at a pressure less than ambient pressure surrounding ‘2’, which may be greater than the hydrostatic pressure of ‘1’. In FIG. 33, the process may be undergoing ‘discharging’. During discharging, low density liquid may be released from ‘2’ to ‘1’, generating electricity by powering generator ‘3’. ‘2’ may be located beneath the surface of a body of liquid with greater density than the low density liquid and/or may exist at a greater hydrostatic pressure than ‘1’. If ‘2’ comprises a contractable or collapsible tank, the total volume occupied by the tank or total volume of liquid in the tank may decrease during ‘discharging’. 3 ‘3’ may comprise a pump and/or generator and/or valve. ‘3’ may be employed to generate power from low density liquid transferred from ‘2’ to ‘1’ during discharging. ‘3’ may be employed to pump low density liquid from ‘1’ to ‘2’ during charging. ‘3’ may comprise a pump, which may be reversibly employed as a generator. ‘3’ may comprise a pump separate from a generator. ‘3’ may comprise multiple pumps and generators or reversible pump/generators. ‘3’ may act as a valve which separates relatively high pressure low density liquid in the pipe ‘Line/Arrow Between ‘2’ and ‘3’’ from the relatively low pressure low density liquid in the pipe ‘Line/Arrow Between ‘1’ and ‘3’’. In FIG. 33, ‘3’ may be generating power from the release of low density liquid from ‘2’ to ‘1’, which may comprise discharging the energy storage device. Electricity ‘Electricity’ may comprise a source of electricity or an application requiring electricity or both. ‘Electricity’ may encompass transmission equipment and/or electricity grid infrastructure and/ or applications generating or using electricity. In FIG. 33, ‘Electricity’ may comprise electricity generated by ‘3’ during discharging and/or the transmission and/or utilization of said electricity. In FIG. 33, electricity may be transferred using undersea cables or using underground cables or using subsea cables or using light, or using microwaves, or by conversion into a fuel, or by reversible production of a fuels, or by charging a transportable battery, or may be used by a nearby application, or may be used by an application on land, or may be used by an application on the body of water, or a combination thereof. Line/Arrow Between The present diagram element may comprise a means for ‘1’ and ‘3’ transferring low density liquid from ‘3’ to ‘1’. For example, the present diagram element may comprise a pipe or set of pipes. Said pipe may be compatible with the low density liquid. Line/Arrow Between The present diagram element may comprise a means for ‘3’ and ‘2’ transferring low density liquid from ‘2’ to ‘3’. For example, the present diagram element may comprise a pipe or pipes. The present diagram element may involve a pipe which experiences a pressure difference between internal liquid contents and liquid surrounding the pipe. Said pressure difference may vary depending on the depth of the section of pipe beneath the surface of the water body, the depth of reservoir ‘2’ compared to reservoir ‘1’ or to ‘3’, the hydrostatic pressure difference between reservoir ‘1’ and reservoir ‘2’, and/or the density of the low density liquid and/or the density of the liquid surrounding the section of pipe. In FIG. 33, the present diagram element may involve transferring low density liquid from ‘2’ to ‘3’. Water ‘Water’ may comprise the body of liquid which ‘1’, ‘2’, and/or ‘3’ are situated and/or submerged in FIG. 33.

Example Step-by-Step Description

Charging:

Low density liquid is pumped from reservoir ‘1’ to reservoir ‘2’ using pump ‘3’. Power is stored in the gravitational potential energy and/or hydrostatic pressure difference of the low density liquid stored at reservoir ‘2’ relative to reservoir ‘1’.

Discharging:

Low density liquid is released from reservoir ‘2’ and transferred to reservoir ‘1’, generating electricity using generator ‘3’. Power is generated by releasing energy stored in the gravitational potential energy and/or hydrostatic pressure difference of the low density liquid stored at reservoir ‘2’ relative to reservoir ‘1’.

Example Calculations

The below table shows key metrics on the energy density and cost of the butane in the present gravitational potential energy storage device. Cost figures employ an example butane commodity price of $0.60 USD per gallon.

Difference in Ocean Water Cost of Depth between Wh per Tons of Tons of Tons of Butane Reservoir 1 liter of kWh per m³ Butane Butane per Butane per kWh and 2 (m) Butane of Butane per kWh MWh per GWh (USD) 100 125.7667 0.125766667 4.556056 4556.056 4556056 722.15 200 251.5333 0.251533333 2.278028 2278.028 2278028 361.075 300 377.3 0.3773 1.518685 1518.685 1518685 240.7167 400 503.0667 0.503066667 1.139014 1139.014 1139014 180.5375 500 628.8333 0.628833333 0.911211 911.2112 911211.2 144.43 600 754.6 0.7546 0.759343 759.3427 759342.7 120.3583 700 880.3667 0.880366667 0.650865 650.8652 650865.2 103.1643 800 1006.133 1.006133333 0.569507 569.507 569507 90.26875 900 1131.9 1.1319 0.506228 506.2285 506228.5 80.23889 1000 1257.667 1.257666667 0.455606 455.6056 455605.6 72.215 1500 1886.5 1.8865 0.303737 303.7371 303737.1 48.14333 2000 2515.333 2.515333333 0.227803 227.8028 227802.8 36.1075 2500 3144.167 3.144166667 0.182242 182.2422 182242.2 28.886 3000 3773 3.773 0.151869 151.8685 151868.5 24.07167 3500 4401.833 4.401833333 0.130173 130.173 130173 20.63286 4000 5030.667 5.030666667 0.113901 113.9014 113901.4 18.05375 4500 5659.5 5.6595 0.101246 101.2457 101245.7 16.04778 5000 6288.333 6.288333333 0.091121 91.12112 91121.12 14.443

Notes

Note: Electricity may be transferred from or to an electricity grid or application requiring or supply electricity.

Note: Electricity may be transferred using, for example, undersea or underground or above ground or a combination thereof power lines.

Note: The lines/arrows between ‘1’ and ‘3’ and ‘3’ and ‘2’ may represent the transfer of low density liquid between these process elements. Liquid may be transferred using, for example, pipes or transport vehicles. If liquid is transferred using pipes, it may be desirable for said pipe to be, including, but not limited to, one or more or a combination of the following: located on the surface of the ground, or suspended above the surface of the ground, or located beneath the ground, or comprise a subsurface pipeline, or comprise an underground pipeline, or comprise a pipeline beneath water and above ground, or comprise a pipeline beneath ground and beneath water, or comprise a pipeline above water and above ground.

Note: Expandable or collapsible reservoir may comprise a liquid storage vessel which can expand or contract in volume to allow for the storage of more or less liquid, respectively. The pressure inside said reservoir may be close to or equal to the pressure surround said reservoir. Said reservoirs may include, but is not limited to, expandable or collapsible liquid storage devices, which may include, but are not limited to, one or more or a combination of the following: pillow tanks, or onion tanks, or balloon tanks, or bag tanks, fabric tanks, or bladder tanks, or folding tanks, or flexible tanks, or bellows tanks, or accordion tanks, or liner tanks.

Note: The present invention may comprise a LPG storage facility, or an oil storage facility, or a strategic LPG reserve, or a strategic oil reserve.

Note: The present invention may be employed to store a fuel or commodity chemical, while simultaneously employing said fuel or other commodity chemical as an gravitational electricity storage medium. This may enable the owner or operator of the facility to have an additional source of revenue (the storage or release of electricity), in addition to revenue from the storage of the fuel or other commodity chemical. By employing the present invention as a storage facility, instead of purchasing or leasing the low density liquid, the facility owner may be paid storage fees to store the low density liquid, which may further improve economics of the facility. A proportion of the low density liquid storage in the facility may be available for ‘commodity storage’ while a proportion of the low density liquid storage in the facility may be intended for permanent or semi-permanent storage. The proportion of low density liquid storage available for ‘commodity storage’ relative to the proportion of low density liquid storage intended to be permanently or semi-permanently in the facility may vary by facility and may be dependent on multiple economic factors and the priorities of the facility.

Note: ‘Commodity storage’ may comprise flexible or semi-flexible storage may comprise a portion of the storage facility's low density liquid in storage which may be removed or added on a regular basis for market needs, such as commodity traders or other entities involved with the commodity market. If desired, the proportional low density liquid storage capacity devoted to ‘commodity storage’ may comprise the proportion of low density liquid which can be added or removed without substantially impacting the performance or capacity or capabilities of the electricity storage. The threshold of said ‘substantially impacting’ may vary by facility based on economic factors and facility priorities. ‘Semi-permanent storage’ may comprise long term storage or storage which may be utilized in periodic or very rare instances. For example, applications for semi-permanent storage may include, but are not limited to, storage for a commodity asset backed fund, storage for a commodity asset backed ETF or ETN, or storage for a strategic reserve. Permanent storage may involve low density liquid which is intended to remain in the facility and/or may be necessary for the proper operation of the facility.

Note: Stored low density liquid may be employed as a stored asset or physical asset backing a commodity tracking ETF or other fund. The low density liquid storage facility owner or operator may generate revenue from the electricity markets as an energy storage service, as well as generate revenue from the management fees generated by the ETF for storing the low density liquid backing the ETF. The ability to have these two revenue streams may enable the facility owner or operator to generate more revenue from the facility, or may enable lower CAPEX of the facility, or may enable lower management fees for the ETF, or a combination thereof. To ensure the assets backing the ETF or ETN are sufficiently readily available or transferrable, a portion of the low density liquid may be always stored in storage reservoir ‘1’ to satisfy short term needs of low density liquid.

Note: The temperature of water in the ocean beneath a certain depth may be relatively stable. Liquid in storage reservoir ‘2’ be cooled or heated by the surrounding ocean water temperatures, depending on the ambient temperature conditions surrounding reservoir ‘1’ and the ambient conditions surrounding reservoir ‘2’. For example, the ambient conditions surround reservoir ‘2’ may be colder than the ambient conditions surrounding reservoir ‘1’. In said example, the relatively cool temperatures of liquid transferred from reservoir ‘2’ to reservoir ‘1’ may be harnessed to supply cooling to one or more applications requiring cooling. An example application requiring cooling may be the pump or generator ‘3’. For example, the ambient conditions surround reservoir ‘2’ may be warmer than the ambient conditions surrounding reservoir ‘1’. In said example, the relatively warm temperatures of liquid transferred from reservoir ‘2’ to reservoir ‘1’ may be harnessed to supply heating or enthalpy to one or more applications requiring heating or enthalpy. Said certain depth may comprise less than, greater than or equal to, one or more or a combination of the following: 300 meters, or 400 meters, or 500 meters, or 600 meters, or 700 meters, or 800 meters, or 900 meters, or 1,000 meters, or 1,100 meters, or 1,200 meters, or 1,300 meters, or 1,400 meters, or 1,500 meters, or 1,750 meters, or 2,000 meters.

Note: Due to the low density liquid being a liquid and liquids being essentially incompressible compared to gases, the round trip efficiency of the present pressure and/or gravitational energy storage device may possess a significantly greater round trip efficiency relative to energy storage devices which employ pressurized gases. For example, the round trip efficiency of the present invention may be greater than or equal to 40%, or 50%, or 60%, or 70%, or 75%, or 80%, or 85%, or 90% or 95%.

Note: The low density liquid may possess a low viscosity, for example, a viscosity near, equal to, or less than water. For example, butane possesses a dynamic viscosity of ˜0.2 cP at 1° C., compared to a dynamic viscosity of 1.73 cP at 1° C. for water. Other low density liquids other than or in addition to butane may possess a lesser viscosity than water. Low viscosity may be advantageous, for example, because lower viscosity liquids may enable smaller pipe diameter, lower CAPEX, lower pumping energy losses, greater round-trip efficiency, and greater distances between reservoir ‘1’ and reservoir ‘2’.

Note: Compatibility with low density liquid, compatibility with water or ocean water, biofouling, compatibility with pressure. For pipes transferring low density liquid, the pressure difference between the low density liquid inside the pipe and the water surrounding the pipe increases with decreasing depth beneath the surface of the water. To, for example, minimize CAPEX, the pressure rating of the pipe may increase with greater pressure difference. For example, pipe near reservoir ‘2’ may possess lower pressure rating (and/or may be lower cost) and pipe near reservoir ‘1’ may possess greater pressure rating (and/or may be greater cost).

Note: Reservoir ‘2’ and/or reservoir ‘1’ may be anchored or connected or fixed or tethered to the land on the bottom of the body of liquid (e.g. body of water).

Note: Storage reservoirs or tanks may include, but are not limited to, one or more or a combination of the following: a pillow tank, or an onion tank, or a balloon tank, or a bag tank, or a fabric tank, or a bladder tank, or a folding tank, or a flexible tank, or a bellows tank, or an accordion tank, or a liner tank, or a rigid tank, or a piston tank, or an actuator tank, or a valve tank, or a basin tank, or a cement tank, or a wood tank, or a plastic tank, or a ceramic tank, or a fiber tank, or a composite tank, or a rubber tank, or a flexible tank.

Note: Pipe materials may include, but are not limited to, one or more or a combination of the following: plastic pipes, composite pipes, metallic pipes, fiber pipes, resin pipes, wood pipes, cement pipes, flexible pipes, rubber pipes, rigid pipes.

Note: It may be desirable to attach the first and/or second reservoirs to higher density materials to reduce the buoyance of the reservoirs. In the case of the first reservoir, the distance between the reservoir and land at the bottom of a water body be substantial enough to justify the attachment of higher density materials to the first reservoir to reduce the cost of tethering cables. Tethering cables may be employed to counteract the buoyancy of a reservoir and/or to ensure the reservoir is in an appropriate location relative to the other reservoir(s). In some embodiments, the distance between the first reservoir and land at the bottom of a water body may be sufficiently substantial the attachment of higher density materials to the first reservoir costs less than the cost reduction in the of tethering cables.

Note: In some embodiments, the location of the first reservoir may be maintained using a dynamic positioning system. A dynamic positioning system may employ various sensors, or GPS, or radar, or other positioning instruments to inform an operating system of changes in the current position and/or changes in position of the first reservoir and/or external thrust vectors, such as currents. If the position changes of the first reservoir changes and/or if a thrust vector is detected, aquatic or marine engines may be employed to counteract said external thrust vectors and/or changes in position to ensure the first reservoir maintains a desirable position. If desirable, the higher density material attachments to the first reservoir may make the first reservoir at a similar density or neutral density relative to the surrounding water body. If desirably the first reservoir may employ mechanisms to dynamically adjust its density, using, for example, the addition of higher density material, the addition of lower density material (for example: low density liquid or a gas, such as air), the release of higher density material, or the release of lower density material). Said mechanism(s) to dynamically adjust density may also be incorporated within a dynamic positioning system. A dynamic positioning system may also be employed in the second reservoir.

Note: Collapsible or contractable may involve a structure or vessel or tank which can decrease in occupied volume or storage capacity reversibly.

Note: Expandable may involve a structure or vessel or tank which can increase in occupied volume or storage capacity reversibly.

Note: Lower density liquid may be soluble or partially soluble in the higher density liquid. Advantageously, the lower density liquid may be separate from the higher density liquid with a physical barrier, which may prevent the dissolution of lower density liquid in higher density liquid. For example, said physical barrier may involve a storage tank liner or walls or pipes or a combination thereof.

Note: In some instances, low density liquids or liquids with a density less than water may have a boiling point near or less than the outside air or water temperature and/or may possess a large vapor pressure at the temperature of the outside air or water. In said instances, it may be desirable for the first reservoir to be a pressurized or rigid tank. For example, a pressurized or rigid storage tank may enable low density liquid to remain at a liquid phase while being at a temperature above the low density liquid's atmospheric pressure boiling point. In said instances wherein a rigid or pressurized tank is employed at the first storage reservoir, when liquid, such as low density liquid, is removed from the first storage reservoir, the total volume of the rigid or pressurized tank may remain the same. A volume in the tank formerly occupied by liquid phase low density liquid may instead be occupied by gas phase low density liquid. Said gas phase low density liquid may exist in the head space above liquid phase inside the tank, such as liquid phase low density liquid. When liquid, such as low density liquid, is added to the first storage reservoir, the total volume of the rigid or pressurized tank may remain the same. A volume in the tank formerly occupied by gas phase low density liquid may instead be occupied by liquid phase low density liquid. Example low density liquids which may be applicable may include, but not limited to, Liquefied Petroleum Gas (LPG), or propane, or butane, or diethyl ether, or dimethyl ether, or methoxypropane, or methanol, or acetone, or pentane, or hexane, or petroleum ether, or methoxyethane, or liquid natural gas (LNG), or gasoline, or Diisopropyl ether, or alkanes, or alkenes, or alkynes, or cycloalkanes, or a combination thereof.

Note: The present invention may employ devices for leak detection and/or leak prevention. Additionally, the present invention may employ methods to minimize losses or damage caused by a leak. For example, a containment mechanism, such as, for example, including but not limited to, a liner, or blanket, or tarp, or fabric, or funnel, or float, or other containment mechanism, or a combination thereof, may be placed above or suspended above the second reservoir and/or pipes and/or pipe connections. In the event of a leak, low density liquid may rise from the leak and may be captured or caught by said containment mechanism. Said containment mechanism may be effective because low density liquid may tend to float and said containment mechanism may cover a portion or the entire surface area of the second reservoir and/or pipes and/or pipe connections above said second reservoir and/or pipes and/or pipe connections. Low density liquid captured by said containment mechanism may be, if desirable, funneled within said containment mechanism and, if desirable, may be transferred to the surface using a return pipe, where the low density liquid may be recovered. The contact of low density liquid with a portion of the containment vessel or pipe may trigger a sensor or sensors which alert system operators of the need to fix a leak. For example, the said sensor may involve a mechanism for measuring the increased buoyancy of the containment mechanism due to the capturing or containment of leaked low density liquid. For example, said sensor may involve a mechanism for measuring the flow rate of liquid in said return pipe, wherein the presence of at least a certain liquid flow rate may indicate the presence of a low density liquid leak. For example, said sensor may involve a mechanism for detecting low density liquid using spectroscopy or measurements of density or molecular weight or a combination thereof. For example, said sensor may involve measuring the change in mass or pressure or volume in a container connected to said return pipe. For example, said sensor may involve measuring changes in mass or capacity in the first or second reservoir, which may include changes in said mass or energy storage capacity when the process is at a steady state or unexplained changes in mass or energy storage capacity. A first reservoir may employ said containment mechanisms and/or sensors. For example, a first reservoir and/or pump and/or generator may employ said containment mechanisms and/or sensors if, for example, a first reservoir and/or pump and/or generator is located beneath the surface of a water body.

Note: Low density liquid or pipes or vessels or reservoirs or a combination thereof may contain a medium which reacts in the event of or at the site of a leak. For example, a material in the walls of a pipe or vessel or reservoir may react with low density liquid if low density liquid begins to leak. Said reaction may inhibit or block or prevent a leak. Said reaction may involve, including, but not limited to one or more or a combination of the following: an absorption reaction, or a swelling reaction, or a foaming reaction, or an expansion reaction, a reaction to form a solid, a reaction to form a viscous liquid, or a combination thereof. Alternatively, or additionally, the low density liquid or walls of pipes or vessels or reservoirs or a combination thereof may contain a reagent which reacts with water or air or salt in water upon exposure to water or air. Said reaction may inhibit or block or prevent a leak. Said reaction may involve, including, but not limited to one or more or a combination of the following: an absorption reaction, or a swelling reaction, or a foaming reaction, or an expansion reaction, a reaction to form a solid, a reaction to form a viscous liquid, or a combination thereof. Said reaction may involve forming a material which is more easily or readily captured, or a material which is more environmentally friendly, or a material which may inhibit further leakage, or a material which may simplify or facilitate the process of leakage detection, or a material which may reduce the cost or damage associated with a leakage. For example, said reaction may involve forming a liquid of a certain color or said reaction may involve a tracing reagent.

Note: Low density liquid or pipes or vessels or reservoir or a combination thereof may contain a tracing chemical or reagent which may facilitate leak detection. For example, parts or components of pipes or vessels or reservoir may contain a material, which, when exposed to water, or salt water, or low density liquid, or air, or a combination thereof, may change one or more properties to facilitate detection of leaks or wear or other forms of damage or exposure. For example, said properties may include, but are not limited to, color, electrical conductivity, electrical resistivity, thermal conductivity, surface texture, surface morphology, absorbance spectra, vibration frequency, flexibility, temperature, density, rigidity, or a combination thereof.

Note: The temperature beneath a water body and the temperature above a water body may be different. Additionally, water bodies themselves may possess a range of different temperatures, which may correlate with depth. The temperature of a water body relative to its depth may be known as a water body thermocline. In ultra-deep water bodies, such as an ocean or lake, the temperature of a water body below about 1000 meters or about 1250 meters or about 1500 meters ranges from about 3 to 8° C. because water is generally most dense at about 4° C. For example, in the ocean, the temperature of the water below 1500 meters is generally near 4° C., even if the temperature of the water at the ocean surface is warm, such as, for example, greater than 15° C. or greater than 20° C. In the present invention, the second reservoir may be located at a different depth than the first reservoir. The temperature of the water surrounding the second reservoir may be relatively constant or stable, if, for example, the second reservoir is located at a depth beneath a water body of greater than 100 meters, or 200 meters, or 300 meters, or 500 meters, or 700 meters, or 900 meters, or 1000 meters, or 1250 meters, or 1500 meters. The temperature of the air or water adjacent to or surrounding the first reservoir may be different from the temperature off the water surrounding the second reservoir. The temperature difference between the second reservoir and the first reservoir may be beneficially utilized or harnessed. For example, if the temperature of the second reservoir is less than the first reservoir or the temperature of things adjacent to the first reservoir, power may be generated from the difference in temperature between liquid returning from the second reservoir and the surrounding ambient temperature near the first reservoir or the temperature inside the first reservoir or another heat source or thermal source or enthalpy source. For example, if the temperature of the second reservoir is greater than the first reservoir or the temperature of things adjacent to the first reservoir, power may be generated from the difference in temperature between liquid returning from the second reservoir and the surrounding ambient temperature near the first reservoir or the temperature inside the first reservoir or another cold source or heat sink or enthalpy sink. For example, if the temperature of the second reservoir is less than the first reservoir or the temperature of things adjacent to the first reservoir, liquid from the second reservoir may be employed as a cooling medium or cooling source or for district cooling to provide valuable or useful cooling to one or more applications requiring cooling. For example, if the temperature of the second reservoir is greater than the first reservoir or the temperature of things adjacent to the first reservoir, liquid from the second reservoir may be employed as a heating medium or heat source or for district heating to provide valuable or useful heating to one or more applications requiring heating. For example, if the temperature of the second reservoir is less than the first reservoir or the temperature of things adjacent to the first reservoir, liquid from the second reservoir may be employed as a cooling source to power or facilitate a desalination process or a process for removing water from gas streams or air. For example, if the temperature of the second reservoir is less than the first reservoir or the temperature of things adjacent to the first reservoir, it may be desirable to insulate said first reservoir or one or more pipes. Said insulation may enable the first reservoir to remain at a cooler temperature, which may be advantageous, for example, if the low density liquid has a low boiling point or is volatile and minimizing temperature in the first reservoir minimizes pressure in the first reservoir. Said insulation may also prevent the formation of condensation on a tank.

Note: The present invention may also be employed as a means for ocean thermal energy conversion (OTEC).

Note: If desirable, one or more components of the present invention may be heated or cooled or temperature controlled or a combination thereof.

Note: Low density liquid may possess a freezing point less than water, which may be advantageously utilized. For example, the first reservoir may be employed as a cold or thermal storage unit, for, for example, providing cooling for a refrigerated or frozen storage facility. Said cold storage may be employed, for example, to optimize energy consumption or for grid load shifting or load curtailment. For example, the first reservoir may be employed as a cryogenic cold storage or thermal storage unit. Alternatively or additionally, cool low density liquid may be employed as a low temperature heat transfer fluid and/or as a low temperature thermal storage medium. For example, low density liquid may be employed in applications which require cooling, which may include, but are not limited to, one or more or a combination of the following: district cooling, or cooling for a desalination facility, or cooling for a power plant, or cooling for an air separation unit, or cooling for a liquification facility, or cooling for a HVAC system. For example, LNG gasification facilities may produce significant waste cooling. LNG gasification facilities may employ low density liquid in or from said first reservoir as a heat source or enthalpy source, cooling said low density liquid in the process. Due to its potentially lower freezing point, low density liquid may be cooled to a lower temperature than water while remaining at a liquid phase, enabling heat transfer or large scale thermal storage or both at temperatures near, at, or below the freezing point of water. Additionally, because the first reservoir is interconnected to the second reservoir and the second reservoir may be located at a relatively consistent ‘cold’ temperature, ‘warm’ low density liquid may be near 4° C. or otherwise below ambient temperature. Advantageously, because ‘warm’ low density liquid may be significantly less than ambient temperatures, more energy may be recovered from ‘cold sources’ than if said low density liquid was near or at ambient temperatures.

Note: Low density liquid or high density liquid or both may be employed as a heat transfer fluid, or as a thermal storage fluid, or may be employed in ocean thermal energy conversion.

EXAMPLE EXEMPLARY EMBODIMENTS

1. A system for storing or generating electricity comprising:

a first storage reservoir configured to be near the surface of a body of water and configured to store a fluid which has a lower density than water;

a second storage reservoir configured to be located below the surface of the body of water;

a pump; and

a generator;

wherein the pump, generator, and the first and second reservoir are operatively connected such that electricity is stored by displacing water adjacent the second storage reservoir by pumping low density fluid in the first storage reservoir to the second storage reservoir and electricity is generated or discharged by allowing the low density fluid in the second storage reservoir to return to the first storage reservoir; and, wherein the water and the fluid which has a lower density than water are both in liquid form. 2. The system of Embodiment 1 wherein said second storage reservoir is expandable, contractible, or collapsible. 3. The system of Embodiment 1 wherein said second storage reservoir is a pillow tank, an onion tank, a balloon tank, a bag tank, a fabric tank, a bladder tank, a folding tank, a flexible tank, a bellows tank, an accordion tank, or a liner tank. 4. The system of Embodiment 1 wherein said second storage reservoir comprises a concave region with an opening near the bottom of said concave region wherein said opening is open to the body of water. 5. A system for storing or generating electricity comprising: a first storage reservoir configured to store a fluid which has a lower density than water; a second storage reservoir configured to be located below a surface of a body of water wherein the second storage reservoir is at a greater depth beneath the surface of a water body than the first storage reservoir; a pump; and a generator; wherein the pump, generator, and the first and second reservoir are operatively connected such that (1) electricity is stored by pumping low density fluid in the first storage reservoir to the second storage reservoir to displace water; or (2) electricity is generated or discharged by allowing low density fluid in the second storage reservoir to return to the first storage reservoir; or (3) both (1) and (2); wherein the water and the fluid which has a lower density than water are both in liquid form. 6. The system of Embodiment 5 wherein the displaced water is in the second storage reservoir. 7. The system of Embodiment 5 wherein the displaced water is water within the body of water and wherein the displaced water is adjacent the second storage reservoir. 8. The system of Embodiment 5 wherein the water pump and the generator are the same unit. 9. The system of Embodiment 5 wherein said first storage reservoir, said second storage reservoir, or both comprise an expandable or contractible or collapsible structure. 10. The system of Embodiment 5 wherein said first storage reservoir, said second storage reservoir, or both comprise a pillow tank, an onion tank, a balloon tank, a bag tank, a fabric tank, a bladder tank, a folding tank, a flexible tank, a bellows tank, an accordion tank, or a liner tank. 11. The system of Embodiment 5 wherein said second storage reservoir comprises a concave region with an opening near the bottom of said concave region open to the body of water. 12. The system of Embodiment 5 wherein said second storage reservoir is tethered to the bottom of said water body. 13. The system of Embodiment 5 wherein the fluid having a lower density than water comprises a hydrocarbon liquid. 14. The system of Embodiment 5 which further comprises a dynamic positioning system to maintain or adjust a position of the first reservoir, the second reservoir or both. 15. The system of Embodiment 5 further comprising an operative connection to an electricity grid or electricity transmission infrastructure. 16. The system of Embodiment 5 wherein said second storage reservoir is configured to store a fluid which has a lower density than water. 17. The system of Embodiment 5 wherein said first and second reservoirs are connected by one or more pipes. 18. The system of Embodiment 5 wherein said pump and generator comprise a single unit. 19. The system of Embodiment 5 wherein said first reservoir is configured to be located beneath the surface of a water body. 20. The system of Embodiment 5 wherein the fluid having a lower density than water comprises propane, butane, LPG, pentane, hexane, or a mixture thereof. 21. The system of Embodiment 5 wherein the fluid having a lower density than water comprises an alcohol, an ether, an ester, or a mixture thereof. 22. The system of Embodiment 5 wherein the fluid having a lower density than water comprises methanol, ethanol, propanol, acetone, dimethyl ether, diethyl ether, or a mixture thereof. 23. The system of Embodiment 9 wherein said second reservoir is configured to collapse or contract during discharge. 24. The system of Embodiment 26 wherein said collapsing or contracting is due to water adjacent said second reservoir displacing the fluid having a lower density than water. 25. The system of Embodiment 9 wherein said second reservoir expands during charging. 26. The system of Embodiment 25 wherein said expanding is due to the fluid having a lower density than water entering the second reservoir and displacing water adjacent said second reservoir. 27. The system of Embodiment 19 wherein said first reservoir is configured to be tethered to a bottom of the water body. 28. The system of Embodiment 19 wherein said first reservoir is configured to be attached to a material with a greater density than water to reduce buoyancy. 29. The system of Embodiment 19 wherein said first reservoir is configured to be attached to a material with a greater density than water, be neutrally buoyant, and wherein the first reservoir is configured such that its position is maintained or adjusted with a dynamic positioning system. 30. The system of Embodiment 5 wherein said second reservoir is attached to a material with a greater density than water to reduce buoyancy. 

What is claimed is:
 1. A system for storing or generating electricity comprising: a first storage reservoir configured to be near the surface of a body of water and configured to store a fluid which has a lower density than water; a second storage reservoir configured to be located below the surface of the body of water; a pump; and a generator; wherein the pump, generator, and the first and second reservoir are operatively connected such that electricity is stored by displacing water inside the second storage reservoir by pumping low density fluid in the first storage reservoir to the second storage reservoir and electricity is generated or discharged by allowing the low density fluid in the second storage reservoir to return to the first storage reservoir; wherein the water and the fluid which has a lower density than water are both in liquid form; and wherein said second storage reservoir is rigid.
 2. The system of claim 1 wherein said second storage reservoir comprises a concave region with an opening near the bottom of said concave region wherein said opening is open to the body of water.
 3. A system for storing or generating electricity comprising: a first storage reservoir configured to store a fluid which has a lower density than water; a second storage reservoir configured to be located below a surface of a body of water wherein the second storage reservoir is at a greater depth beneath the surface of the water body than the first storage reservoir; a pump; and a generator; wherein the pump, generator, and the first and second reservoir are operatively connected such that (1) electricity is stored by pumping low density fluid in the first storage reservoir to the second storage reservoir to displace water inside the second storage reservoir; or (2) electricity is generated or discharged by allowing low density fluid in the second storage reservoir to return to the first storage reservoir; or (3) both (1) and (2); wherein the fluid which has a lower density than water is in liquid form in at least the second storage reservoir; and wherein the second storage reservoir is rigid.
 4. The system of claim 3 wherein the second storage reservoir is a tank comprising cement, wood, plastic, ceramic tank, fiber tank, composite, or rubber.
 5. The system of claim 3 wherein the pump and the generator are the same unit.
 6. The system of claim 3 wherein said first storage reservoir comprises an expandable or contractible or collapsible structure.
 7. The system of claim 3 wherein said first storage reservoir comprises a pillow tank, an onion tank, a balloon tank, a bag tank, a fabric tank, a bladder tank, a folding tank, a flexible tank, a bellows tank, an accordion tank, or a liner tank.
 8. The system of claim 3 wherein said second storage reservoir comprises a concave region with an opening near the bottom of said concave region open to the body of water.
 9. The system of claim 3 wherein said second storage reservoir is tethered to the bottom of said water body.
 10. The system of claim 3 wherein the fluid having a lower density than water comprises a hydrocarbon liquid.
 11. The system of claim 3 which further comprises a dynamic positioning system to maintain or adjust a position of the first reservoir, the second reservoir or both.
 12. The system of claim 3 further comprising an operative connection to an electricity grid or electricity transmission infrastructure.
 13. The system of claim 3 wherein said second storage reservoir is configured to store the fluid which has a lower density than water.
 14. The system of claim 3 wherein said first and second reservoirs are connected by one or more pipes.
 15. The system of claim 3 wherein said pump and generator comprise a single unit.
 16. The system of claim 3 wherein said first reservoir is configured to be located beneath the surface of the water body.
 17. The system of claim 16 wherein said first reservoir is configured to be tethered to a bottom of the water body.
 18. The system of claim 16 wherein said first reservoir is configured to be attached to a material with a greater density than water to reduce buoyancy.
 19. The system of claim 16 wherein said first reservoir is configured to be attached to a material with a greater density than water, be neutrally buoyant, and wherein the first reservoir is configured such that its position is maintained or adjusted with a dynamic positioning system.
 20. The system of claim 3 wherein the fluid having a lower density than water comprises propane, butane, LPG, pentane, hexane, or a mixture thereof.
 21. The system of claim 3 wherein the fluid having a lower density than water comprises an alcohol, an ether, an ester, or a mixture thereof.
 22. The system of claim 3 wherein the fluid having a lower density than water comprises methanol, ethanol, propanol, acetone, dimethyl ether, diethyl ether, or a mixture thereof.
 23. The system of claim 3 wherein said second reservoir is attached to a material with a greater density than water to reduce buoyancy. 